Chassis Report

  INTRODUCTION

The desktop computer case is also known as the chassis. It encloses all of the computer components to protect them from external elements like dust and water. Components like: graphics cards, central processing unit (CPU), hard disk drives and main-board are much more expensive compared to the computer case, so it is very important to enclose the components to avoid any hardware failure inside the computer system. PC component cases computer chassis are usually constructed from steel, aluminum, or plastic; although other materials such as wood, Plexiglas, and Lego have also been used in case designs. A computer case should have extra room inside it in order to add more hardware in the future. This will also help to keep the temperature low for the components. The layout and design of the case, as well as its internals also determine the cooling performance of the entire system. As most computer parts are installed in the case, the case is more than just a box. It plays a very significant role in computer build. The computer case affects the type and number of components that can be installed. PC’s generates a lot of heat, and a cheap case will not be as effective in reducing that heat from inside of the computer.

II.      FACTORS ON CHOOSING CHASSIS

The most important thing to consider while selecting a case is size. A major determinant of the case size is the motherboard, which is the largest part of the computer. There are two specifications which are taken under consideration while selecting a computer case: NON-FUNCTIONAL; meaning the aesthetic and the colour selection of the case; and FUNCTIONAL; meaning the size and shape of the case.

a. TYPES OF CASE SIZE

b. Case Form factor/Motherboard Compatibility

c. COOLING

d. CASE MATERIAL

e. NUMBER OF BAYS

f. CASE DESIGN

g. MISCELLANEOU

a.               TYPES OF CASE SIZES

b.               DESKTOP/HTPC CASE

These types of cases are designed to utilise the space on the desktop. These cases are usually placed on top of a desk. These cases are simple and compact.

ADVANTAGES/FEATURES

• Utilize desk space when the monitor is placed on top of the computer.
• It supports Mini ITX .
• General Dimensions: H-3.8”    W-12.8”  D-16.8”
• ·    Zero noise, small footprint and low power.
• ·   Fanless design, with multiple mounting options.
• Fans can be installed on the hard drive mounting brackets or in the front of the enclosure.

DISADVANTAGES: Difficult to upgrade.

RECOMMENDATIONS: The M350 Case is used for digital signage. Easy to carry and can be attached at the back of the signage screen. Minuet 350 is compact and easy to fit underneath the table. It also supports GPU and HSF. It is typically used in analytics and talent management because it supports the applications they need.

• TOWER CASES

These types of cases can be kept on the floor as well, as they are designed in such a way that you can also put them on the desk. Depending on the design/shape, specific number of internal drive bays present inside and the height of the tower, these cases can be further classified into:

Mini-sized Tower cases: These types of cases are bigger than the desktop cases with 2 to 4 internal drive bays.

 ADVANTAGES/features

• Can be placed on top of or below a computer desk.
• Having adjustable brackets allows it to fit vertically and horizontally.
• Supports an 80mm fan
• GENERAL DIMENSIONS: H-13.85”         W-7.08”    D-17.32”
• It has 3 drive bays; one 5.25” and two 3.5”
• It supports Mini ITX & Micro ATX.

DISADVANTAGES: Problem with expandability. Not enough space inside the case.

RECOMMENDATIONS: Compact size with great cooling performance. Good lightweight system that does not hold a lot of powerful components. It also has expandability options available.

(i)                 Mid-sized Tower Cases: These cases are bigger than mini-sized cases. These cases can be easily   expandable according to the requirements needed. These are the most widely used cases worldwide.

ADVANTAGES/features

• These towers can be placed either below or above the computer desk. These cases have the option of expandability for new devices.
• Supports 9 drives in total : External 3X5.25” & internal 6X 3.5”
• Supports up to 5 fans: one top, one rear, two front fans & one on the side of computer case.
• Compatible Motherboards: Mini-ITX, microATX, Standard ATX
• DIMENSIONS:  18″ (H) x 18.3″ (D) x 8.1″ (W)

DISADVANTAGES: None

RECOMMENDATIONS: Descent case with excellent cooling, and is easily upgraded. It supports all types of motherboards. Also supports all high end components like GPU, water cooling and maximum number of fans for good air flow. We use this case in Creative department.

• FULL SIZE TOWER CASES

These cases are bigger than Mid-size cases and are commonly used in the design of servers, mainframes and advanced workstations that can handle multiple applications.

ADVANTAGES/FEATURES

• Excellent case for server machines.
• DIMENSIONS: H-24”  W-8”  D-18”
• Supports more than 6 fans inside the case.
• Motherboard compatibility: E-ATX / ATX / M-ATX/ CEB
• Supports USB 3.0
• Comes with 8 expansion slots and 20 bays
• Weight : 9.2 kgs

DISADVANTAGES: These cases are expensive, heavy & occupy more space.

RECOMMENDATIONS: This case gives maximum performance, cooling and compatibility. IT has the maximum number of drive bays and fan capacity. It has a large amount of space for cable management, and good air flow. We typically use these cases for our server build.

(i)                SHUTTLE CASES

The shuttle is a compressed version of the micro tower and is more boxed shaped than the micro tower. It is ideal for a small work area.

ADVANTAGES/FEATURES

• Low budget PC. Used where there is limited space
• Motherboard compatibility: Mini-DTX, Mini-ITX
• Equipped with 2 expansion slots
• Supports 2 drive bays, one 3.5” and one 2.5.
• Also supports one 120mm fan for intake
• DIMENSIONS: H-8.74”  W-6.93”  D-10.87”

DISADVANTAGE: limited room to add hardware.

RECOMMENDATIONS: Compact case that can fit almost anywhere. The case is capable of swallowing many standard components while keeping everything cooled.

CASE DIMENSIONS CHART

c.    Chassis Form Factor /Motherboard Compatibility

“Form factor” refers to the size; shape and format of motherboards, power supplies and cases.  There are two form factors where the motherboard for the desktop depends:  ATX (Advanced Technology Extended) and BTX (Balanced Technology Extended). In addition, there are cases that also support SSI (Server System Infrastructure) motherboards, which are used in servers.

The ATX form factor was designed to replace the AT and baby AT form factor. There are different types of categories that fall under this form factor such as:

• Micro ATX and ATX(Smaller boards)
• EATX or Extended ATX(Larger boards)

The BTX form factor was designed to replace aging ATX motherboards in 2005 by adding more cooling and less fans, resulting in PC’s running more quietly. The reason for their failure was the rise of energy-efficient components, which require less power and produce less heat waste as compared to BTX boards.

TYPES/SIZES OF MOTHERBOARDS

NOTE: The ATX form factor is common worldwide. Very few retailers in the market have BTX motherboard/cases. But there are several ATX/BTX all-compatible cases in the market, and users can easily convert the case to fit the motherboard form factor required                     

The following is the compatibility check for case-motherboard Size:

 COMPATIBILITY CHECK

d.  CASE MATERIAL

Generally Cases are made up of Steel that is SECC-steel (Electrically chromate coated or aluminium). After choosing the case size, the next step is to choose the case material.

The three most common materials for case construction are:

(i)                 STEEL: Due to inexpensiveness and strong strength, steel is the most common material used to build computer cases. 

SECC: Stands for: Steel, Electro galvanized, Cold Rolled, Coil. It is cheaper, heavier and less prone to   producing vibrations. It also never rusts.

(ii)  ALUMINIUM:  On other hand Aluminum is more expensive than steel, but it looks better than steel and from other people’s point of view aluminium conducts/transfer heat more efficiently than steel. Aluminium leads to cool case temperatures and longer component life.

(iii) Acrylic: Acrylic is not good conductor of heat. Acrylic is designed for modders due to its  transparency and relative cutting ease. It has no EMI prevention. Acrylic is more expensive if has a decent quality thicker acrylic, but it is a little quieter than metal. Acrylic cases are usually completely transparent.

NOTE: An aluminium case can be flimsy, and can increase noise levels from its vibrations. A steel case however, is more solid and is less prone to creating vibrations.

COMPATIBILITY CHECK

e. DRIVE BAYS

Different sized cases can hold different numbers of components. When assessing the size of computer cases, the number of bays should also be taken into consideration.

There are two types of drive bays in a computer: 5.25” and 3.5” bays. Always make sure that there are enough expansion bays in your case to hold all of your components.

5.25” BAYS

You can find these bays located generally on the top section of the computer. These bays are most commonly used for the optical drives such as DVD and Blu-Ray. These bays can also be modified to hold 3.5” drives that can be easily removed. To fit a 3.5” drive in a 5.25” bay you can use convertors. There are two types of converters:

• One 5.25” bay convertor which holds only one 3.5” drive
• Three 5.25” bays convertor which holds five 3.5” drives.

3.5” BAYS

These bays are located underneath the 5.25” bays. These types of bays hold identical drives; however, external bays have a hole cut for them at the front of the computer. These are used for devices such as card readers and floppy disk drives. Internal 3.5” drive bays are designed almost exclusively for holding hard drives. Some of the more expensive cases now provide a bracket for a 2.5” drive.

Type of case with number of bays supported:

f.  COOLING

Cooling performance of a case is very much dependent upon its design, as almost every component inside the computer case generates heat. The main generators of heat in cases are the CPU and Video Card. The layout and design of a computer case determines to a great degree the amount of airflow within the case and consequently, the cooling performance of the system. Cooling of the CPU begins with choosing the correct heat sink. Fans should be aligned in such a way that brings cool, fresh air in at the bottom front of the case, and exhausts warm air from the top rear.

THINGS TO KEEP IN MIND WHILE ASSEMBLING A COMPUTER

• The colder the cooling air, the more effective the cooling.
• Supply cool air to the hot components as directly as possible.
• Use cool intake air if possible. avoid inhaling exhaust air (outside air above or near the exhausts). For example, a CPU cooling air duct at the back of a tower case would inhale warm air from a graphics card exhaust. Moving all exhausts to one side of the case, conventionally the back helps to keep the intake air cool.

(i) FANS: Fans are classified by their sizes.  Fan performance is usually measured in CFM (cubic feet per minute).  The larger the size of the fan, the less noise it will make while pushing and pulling the air in and out of the computer case. Certain computer cases do not come with their own case cooling fans, but you can add extra fans or change existing case fans for better ventilation or to lower the noise. Make sure that the case supports additional fans. We prefer high static pressure fans for cases. Fans that have a higher air pressure rating can maintain its rated air flow at higher resistances. A resistance for a fan would be something like a radiator. A Case fan with Water cooling is a good example of the high static pressure rating.

NOTE: Make sure that the fan you have installed inside the computer is working. In some chassis’ you can see your fan running through the transparent window while in other chassis’ you need to crack it open and carefully turn it on to check whether or not it’s working.

TYPES

• 40mm/60mm: These fans are used with GPU’s. They are typically used on smaller chips.
• 80mm/92mm: These fans are installed at the back of the case eg: HTPC cases like Minuet 350.
• 120mm: Common fans used with all heat sinks, intake, bottom and top in Antec 300, 100, 1200, P193, CM 341, CM 342.
• 140mm: Used in Servers(Antec P193) and Mid tower cases like Antec 300, Antec 100
• 200mm: These fans are generally used in server builds.

(ii) SIDE AIR VENT: If a case has a side air vent directly above the CPU, cooling will be more effective and the fresh air will directly hit the CPU. This process will also make the CPU fans quieter.

Cases without a side vent has air coming into the computer from the front, passing the hard drives before reaching the CPU without ventilation. By the time the air reaches the CPU, it’s only a little cooler than the CPU itself.

NOTE: Make sure there are no open holes at the back of the computer case because the open holes it will affect the air flow within the case. If more air than required goes into the computer, the fans performance is reduced.

g.               CASE DESIGN:

TOOL-LESS: We prefer a tool-less design for a case, as cases with the tool-less design allows for quick and easy access to the interior of the system. This means you can install and remove computer parts without the use of tools. Practically all components can be mounted inside the case without tools. PCI-slots and optical drives are fixed with tool-less solutions. A good example of a tool-less design is the DELL Minuet Tool-less Silent PC Case. All DELL computer cases at the PMP are tool-less.

(i)  EXPANSION SLOTS

The purpose of the expansion card is to expand on features which are not provided by the motherboard. Generally all motherboards contain expansion slots for adding more memory and graphic cards. Expansion slots for PCs come in two basic sizes: half and full-size. The expansion slots provided by the case are not that different from those on a motherboard. The expansion slots on the case are designed to match up with the expansion slot positions on your motherboard to secure the add-in cards, as well as allow the connection of other devices to these add-in cards possible.

NOTE: Case expansion slots should not be less than your motherboard (all slots, including video card slots).

(iii)  FRONT PANEL PORTS

Front ports refer to a group of I/O ports located near or on the front panel of the computer case. They may also be located above or to the side of the front panel and are designed for easy access, as users will not have to reach for the ports on the rear panel of the case to connect or disconnect peripherals. Most front ports are a combination of USB ports and audio ports.

• USB: These connectors are used to add extra external USB ports (such as USB2.0 OR USB 3.0), or to connect internal USB devices (such as internal card readers). Each connector supports either two USB ports or a single device. Most new motherboards have at least two internal USB headers (connectors), with some having as many as four.

• Front panel ports are generally located directly on the front cover of a computer case, but they may also be found on one side of the case.

(iii)  SIDE PANEL WINDOW

Side panel windows or transparent side panels allow you to see the components working without removing the side panel. These are quickly becoming a necessity for gamers who want to install UV-sensitive or LED lights in the system. With these modes, a system looks good in the dark.

h. MISCELLANEOUS/Extra features

(i) PSU: A PSU is not included with every case. A case should have an adequate power supply to give power to all the components in the computer system in terms of wattage and quality. It is recommended that a standalone power supply should be purchased from a reputable manufacturer.

AIRFLOW: Cool air is drawn into a case from fans in the front panel. The incoming air helps cool components as it moves through the case, becoming warm in the process. It is evacuated through the PSU and out the rear by the PSU fan. Manually varying a high airflow PSU fan can cause CPU temperatures to be affected as much as 5-6 degrees Celsius.

(ii)  USB 3.0 bracket: It is beneficial to purchase a case that comes with front panel USB 3.0 bracket. It should be compatible with the USB 3.0 that comes with motherboard itself eg: Antec 100 comes with the USB3.0 compatible bracket, but for Antec 300 we buy that same bracket separately.

(iii) SSD BAY: Some cases come with detachable SSD cage.

III     TOOLS TO BUILD A PC

To build a PC we generally need phillips Screwdrivers. But there are a few more tools which makes the building of a PC easy.

TYPES OF TOOLS

• Screwdrivers: – Used for philips head screws
• Needle-Nose Pliers: – Use to grab jumper caps
• Parts Retriever: – Used to grab the lost screw or any other lost part.
• Diagonal Cutter: – Used to cut the cable ties.
• ESD Wrist Strap: - Used to cut electrostatic discharge from human body.

TYPES OF SCREWS

STANDOFFS:

 Standoffs are the round plastic or metal separators that separate the motherboard from the case, so that the components at the back of the motherboard do not touch the case. Metal standoffs also provide an electrical ground connection between the motherboard and case, while plastic standoffs do not. It also prevents the motherboard from moving around, which can cause damage to the components. Finally, the standoffs give the motherboard support when you are installing other components.

Types of standoffs:

• male portion 6-32
• female portion M3
• Plastic Screws

• Fan screws: Used for fans.
• Optical drive screws: Used for optical drives.
• Thumb screws:  Used to close the cases.
• Phillip head: Used for hard drives.
• MOBO hex: Used for Big size motherboards and big size hard drives.
• Small HDD hex: Used for small motherboards and small HDD’s.
• Rubber fan: These are anti-vibrant screws for the fans.
• Long screws:  Used for water cooling fans.
• Super micro: Used to build servers for super micro cages.

IV. MECHANISM FOR AIR FLOW

In order to avoid over heating inside a computer, we install fans to increase the air flow inside the computer. Usually there are two fans in a desktop computer case. One fan is directly connected to the CPU close to the chip, and the other is externally connected to the case by itself. Usually other components like PSU and GPU have fans attached to them by default for air cooling. When we turn on the computer, these fans boost the circulation of air inside the case and try to cool or maintain the room temperature within the case.

UNDER PRESSURE: The basic principle to keep the case well ventilated is called the “pressure rule”.

Two factors are responsible for it:

• Position and directions of ventilators
• State of the case

There are three main airflow models, each having its advantages and disadvantages:

• Negative Pressure –Negative-pressured cases have a larger exhaust than intake. When we turn on the computer, a negative pressure gradient is formed, sucking the hot air out of the case.

•  Equalized Airflow –This is when you have equal air intake and exhaust. This is the most common and works by creating a wind tunnel.

• Positive Pressure – Positive-pressured cases have a larger intake than exhaust. The cases with positive pressure allow the new air to be constantly fed in and push hot air out of the case, replacing it with cool air. Forcing more air into the system than pushing air out causes positive pressure. This happens due to an imbalance in the number or strength of fans. eg: Silverstone SG07 employs a positive pressure layout with all intake areas fitted with removable filters so dust will not accumulate inside.

RECOMMENDATION: Equalized airflow is recommended for computers to maintain the equal pressure inside the case.

NOTE:  If the computer has negative pressure, it will suck the air through all the holes on the chassis. On the other hand, if it has positive pressure it will throw air out of the chassis .The flow rate of the airflow can be calculated by adding the rates of flow (in CFM,) of all intake fans and subtracting the exhaust ones. If the result is positive, the case will be positively-pressured and vice-versa.

Example: A 120mm intake and an 80mm exhaust is a very good way to pump case pressure to a stable positive.

Cooling can be obstructed by:

• Dust acts as a thermal insulator and obstruction in airflow. It affects heat by reducing heat sink and fan performance.
• Poor airflow including turbulence due to friction against impeding components such as cables, or improper orientation of fans, can reduce the amount of air flowing through a case.
• Poor heat transfer due to a lack of/poor application of thermal compounds and sufficient surface area of heat sinks to radiate off the heat.

NOTE: Sometimes slow performance of computer has nothing to with the software or a virus or limited RAM. Sometimes it’s just overheating inside the case.

V.        CABLE MANAGEMENT

Cable management refers to the organizing and securing of cables inside the computer case. Cable management is a very important part of the computer builds due to the complexity of the configurations, and increased number of cable connections required in order to attach additional value-adding computer components.

CABLE ROUTING:
Effective cable routing will allow you to keep your cables organized, reduce the risk of damaging cables and allow for affective cooling.                                                            

Cable management from beginning to end:

As you can see in following 3 pictures, the cable routing is less than optimal. If we avoid cable management for this computer, the system will over-heat due to limited airflow and the computer will look messy.

To do the cable management all we need is a cable tie. Tie clump of wires with cable ties. And wrap it around the bar if any bar is available in case. Or we can hide cables behind the rear panel.

PROCESS:

• Start by taking out the big power cable and removing all other power cables which are connected to motherboard. Remove all of the IDE Cables and SATA cables for the hard drive, DVD drives, floppy drive and all miscellaneous devices you might have.
• Always be careful and try to remember the power, reset, speaker, and front I/O plugs once removed can be difficult in putting back into the proper locations, unless you have motherboard’s manual.
• You can take pictures before taking those cables so you have a reference as to where to put the cables back.
•  After removing all cables, unplug all of the Molex connectors; the ones which come out from the power supply.
• After hiding and tying it with cable ties start again by plugging in IDE cables.
•  The best part of the power supply is that it comes with long cables which are easy to extend up to the level you want. Sometimes they are too long so this is where the hiding cables in the side panel behind the motherboard comes in handy.
• The 6-pin connector to power the CPU (typically located at the top of the motherboard) usually only requires a four or five inch cord, even though they often give a foot or longer to work with. The excess wire can be tucked in behind the motherboard. This same thing applies to every other cable that are longer than required or the cables which are not required at all.

VI.       CASE MODIFICATION:

Modifying a computer in any non-standard way is considered as a case mod. Generally the case is modified to improve a computer’s performance.

COMMON MODIFICATIONS ARE:

• Window mods: This modification is generally done to the left side panel of the case. Manufacturers now offer cases with the windows pre-installed or replaceable side panels with a window installed.
• Lighting mods: Lighting mods refer to lighting inside the computer cases. This is obtained by putting LCD fans or electroluminescent wire lights inside the case.
• Spray paint: Painting a case is another method of distinguishing your work from others.
• Vinyl dye: Re-colouring the plastics of a case, keyboard, mouse and speakers is another method of highlighting your system and making it different than the rest.
• Cooling mods: This is the most common modification. These types of modifications are done to improve the airflow inside the cases and improve the overall performance of the computer. The most common one is simply drilling a place for a new fan, or removing a fan grill. Other examples include:  air ducts, water cooling, filtering and sealing openings to promote better air flow.

This modification is the one in which we use here at the PMP:’

(i)                     BY adding water coolers in computers.

(i)                  Removing metal shield from the front panel for more air cooling

TOOL WE USE TO CUT THE METAL IS CALLED A DREMMEL

VII.      CASE REVIEWS

How to Review case specs while buying a new computer chassis?

As we know, the computer case is an important part of the system. So while buying computer case, buy the case that has enough space to fit all your hardware components. Typical mid-tower ATX cases provide good balance of bays and features.

HOW TO REVIEW A CHASSIS?

We review chassis by checking out some important features that chassis have:

• Material: We look for SECC or STEEL cases because steel is a strong metal that produces fewer vibrations in compared to other metals.
• Cooling: We look for cases that mount the maximum number of fans inside it. eg: front(intake) fans, bottom fans, rear fan, side fans and top fans.
• Drive bays: number of bays eg: internal 5.25”bays, external 5.25” bays, internal 3.5”bays and external 3.5” bays.
• Weight: weight is one of the important factors to look for while choosing a new case. The case should be lighter in weight than the reference case.
•  Expansion slots: Try to pick a case with maximum number of expansion slots.
• Extra features: look at extra features like a USB3.0 bracket, SSD bay, number of fans and PSU that come with the case. It should also have a large spacious interior for all the hardware to fit in easily.
• Water cooling: Cases should have enough space to hold a water cooler radiator.
• Motherboard supported: Before selecting a case, make sure it is compatible with your motherboard.
• Price: Considering the price of a case should take into consideration the number of features.

Short video to review the case specifications:

http://www.youtube.com/watch?v=9FtBh8FFvZM  (Link to review case video)

CASE comparison chart:

http://www.antec.com/pdf/CaseComparison.pdf

VIII.    SOME OTHER CASES WHICH WE USE HERE IN PMP

www.tomshardware.com
www.3dGameMa.com
www.AnandTech.com
www.Benchmark Reviews.com
www.bit-tech.com
www.FiringSquad.com
www.FrostyTech.com
www.GPUReview.com
www.Guru of 3D.com
www.HackaDay.com
www.HardOCP.com.com
www.Hardware Heaven.com
www.HardwareZone.com
www.HotHardware.com
www.LegitReviews.com
www.MADSHRIMPS.com.com
www.Overclockers Club.com
www.PCPer.com
www.PC-STATS.com
www.PCWorld.com
www.Phoronix.com
www.Pro-Clockers.com
www.silentpcreview.com
www.TechPowerUp.com
www.TechRadar.com
www.TechSpot.com
www.Tom’s Guide.com
www.TweakTown.com
www.Vortez Hardware.com
www.X-bit labs.com