Most enclosures support a range of motherboard sizes, each with a few different mounting points. These points connect a layer of the motherboard called the ground plane to the case's mounting tray, reducing signal crosstalk due to radio frequency interference (RFI). Thus, the mounting points are usually grounded.

Misaligned mounting points could contact a hot trace on the motherboard's back side, so case manufacturers usually make them removable via metal spacers called standoffs. It's important to observe the exact location of each mounting hole in the motherboard before placing a standoff in the corresponding tray location. A mistake made here could potentially damage the board, though the most likely result of an improperly-placed standoff is a system that simply refuses to power on. Arrows in the photo below illustrate the matching mounting points where standoffs were placed.

The ATX form factors specifies the size and location of a rectangular plate, called an I/O shield, which fills the gaps around the ports and connectors on the back of the motherboard. That is to say, an I/O shield fits a customized port selection to a standardized hole in the chassis. Cases often include an old-fashioned standard plate that must be snapped out before inserting the new, custom replacement.

Note that the upper tabs of this I/O shield hang down because it arrived in a semi-flattened state. These need to be bent approximately ninety-degrees from the surface to prevent them from blocking nearby ports during motherboard installation. The left tab in the photo below has been bent to the proper orientation. Many of today’s most popular boards instead use foil-faced foam to contact the ports.

Recheck standoff positions before inserting the motherboard at a slight angle, aligning ports with cover plate holes while guiding the board until it rests flat against the standoffs. Grounding tabs or foil-faced foam on the I/O shield will typically push the motherboard out of position, but the board should be easy to push into place. Align one hole perfectly with the standoff and affix a screw, then push the board into alignment for a second hole before tightening the second screw. The first two screws should prevent the board from twisting out of position while installing the remaining screws.

The power supply is usually secured with four coarsely-threaded screws, though it’s not always mounted to the back of the case. Some enclosures relocate the power supply and use an extension cable to place power on the back. Variations in design may demand that the power supply is installed before the motherboard, as specified in the case’s manual or installation guide.
- Step One: Size Up A Case
- Step 2: Select Your CPU
- Step 3: Select Your Graphics
- Step 4: Select A Motherboard
- Step 5: Select Memory
- Step 6: Select Storage
- Step 7: Select A Power Supply
- Other Components
- Step 8: Choose Your Vendor
- Step 9: Preparing For Assembly
- Step 10: Build The Platform (CPU, Cooler, And DRAM)
- Step 11: Install Motherboard And Power Supply
- Step 12: Install Cables, Cards, And Drives
Cheers!
Cheers!
Wonderful as usual toms.. Appreciate it..
Great article! No doubt this is going to help a lot of folks.
Thanks, guys!
I think you missed a section for "SLI - XFire", but it's great overall. Since its a guide for folks with little to no knowledge, I think it would help them to dispel myths and get some facts over XFire and SLI.
Cheers!
First I put the motherboard into the PC (not fastened) to see where the standoffs are going to be placed onto the case. Also I note what routes I'm going use for my cabling. Then I take the motherboard out and insert the standoffs and port plate into the case. Also I take my case cables (power sw, reset sw, USB, front audio and mic cables and put a twist tie around them all and place them near where they are to be plugged into the motherboard. These cables are easy to lose track of.
Next I place the power supply, and "bay devices" (optical drives, non-removable storage, etc) into the case and have those cables attached and either hanging over the outside of the case or routed behind the motherboard tray. This obviously depends on how you determined the cables will be routed earlier.
Then I take my motherboard, put the CPU, RAM, and cooling system on as much as I can. Then I place the whole thing into the case - usually at an angle at first, leading with the side with the RAM (which is normally going behind the case bays in smaller cases) in first.
At this point it's just a matter of aligning the motherboard with the standoffs and port plate. Plug it all in (including the case plugs which are conveniently out of the way and together).
Power it all on and volia!
Otherwise, it was a good article. People who are uncertain of building their own PCs can learn a lot from it.
The 647W is measured at the wall socket, as the article mentions input power. After taking into account the 85% efficiency of their power supply in this example, the PSU is only outputting 549.95W to the PC components at max load. Adding some headroom they come to the 600W PSU recommendation.
Personally I'd like a little more headroom, but the calculations in the article are correct.
Building your own is great fun, and most serious users should probably give it a try at least once in their lives. Given that, I'd recommend an annual "refresh" of this article, with updated info and re-validated links to corresponding reference articles and resource forums.
A great service to your readers!
I wanted to comment on the power supply part of the article. One is the efficiency and the total cost to use versus the front end purchase cost. A less efficient system will obviously create more total heat as wasted energy. But aside from possibly making someones room rather uncomfortable, it also increases your airconditioning energy use. A good rule of thumb is that an AC system will use 50% of the heat energy. To add the total annual cost, multiply that times the percentage of the year that the AC is on. So your example of a 647W system with 85% PSU would give (550W used):
647W - 550W = 93W at plug
93W * 50% = 47W AC energy
Total Energy (summertime) = 93W + 47W = 140W
If the AC were on the while year and the PC were on continuously, this is about $140 annually, or almost $12 per month added electricity in the summer. If you did the same thing with a cheap 70% efficient system, you get $248 annual cost which is $20.63 per month summertime cost. At a difference of $8, it does not take many months (of continuous on!) to make the more efficient PSU make much more sense.
The other topic I wanted to comment on is ESD. I am an engineer and work with ESD issues everyday. It is a very real an poorly understood issue by many because of the often hidden or delayed failures that it causes. ESD many time causes walking wounded damage without an immediate failure, which finally fails several months later. And if you look at websites sell PC parts, many people complain of DOAs. Many, many DOAs are caused by ESD. Memory, CPUs, motherboards, HDDs, and other sensitive systems are often returned as DOA, driving up the cost of the PC enthusiast market and adding frustration. In research texts, they estimate the global electronic failures due to ESD to be 40-60% of the total failures over product life.
So that little $5 ESD wrist strap is money well spent. Buy one and reduce your heartburn.
Charles
So that little $5 ESD wrist strap is money well spent. Buy one and reduce your heartburn.
Charles
The only problem with wrist straps is that most people don't want to be "tied" to anything. They're a great idea that's really rarely needed. Feel free to say otherwise if you live in the desert.