Geeks, online gamers, and power business computer users, such as graphic designers and photo/video editors, generally have a closer relationship with their computers than the average user. In fact, they really have to. In order to get the most out of modern interactive video games, gamers need processor speed, memory, and killer audio and graphics. Designers and photo editors, along with other power users, can do without the hardcore gaming video, but still need the muscle that comes with serious processor and memory power, as well as a more enhanced video/graphics card than a standard business user. For those who are merely geeky, having a workhorse box is simply a way of life.
With that said, it just makes sense that users that fall into one of these categories actually build their computer themselves, or, if they're not quite that into the nuts and bolts of computing, but need customized options, have someone else do it. While it's true that there are a number of customization options available from computer manufacturers, most of the boxes that result are actually only 'semi-custom' computers in that you don't have absolute control over all the components that go into the computer. For this reason, the truly custom box is the answer.
The Case―First Impressions are Important
In reality, the only thing a computer case has to do is protect components and accommodate the fans, heat sinks, power sources, and other 'guts' of the computer. But modern computer cases actually can go further than that, with some separating components into different areas of the case, and resulting in a more efficient functioning of the computer as a whole. Such compartmentalization leads to cooler internal temperatures and greater ease of use. If you're not inclined to go with one of these cases, which are actually quite expensive, a custom case that will hold your selected components and that looks really cool is a good idea. After all, if you're going to build a workhorse that screams, you may as well make it look good too.
Motherboard and Processors
At the very basis of every computer is the motherboard and processor set. Various motherboards are more suited toward one use or another, and it is important to research which motherboards can be utilized with certain chipsets. As for processors, the dual- and quad-core versions on the market now are coming down in price constantly. It is recommended to go with at least two dual-core processors, though those with a less limited budget can actually stack four quad-cores together to create processor power that was virtually unheard of just a few years ago.
Hard Drive and Memory
When hard drives went over the terabyte mark, it was a major step forward, but now it's commonplace. In fact, the cost of SATA hard drives has come down so much that it may be worth considering purchasing four of them and putting them in a RAID array to create further I/O gains. With some 2 TB drives featuring 64 MB cache and coming in at under $100, you could actually build in hard drive redundancy AND have 4 TB of storage with a RAID array. Keep in mind that to properly use a RAID array, it is a good idea to use hardware RAID rather than software RAID, which can lead to latency issues that defeat the purpose of the increased I/O that the array is designed to create.
For those who really want to take things to the next level, small form factor drives are good for smaller cases, though they are generally only necessary in 1U and 2U servers, which must meet certain space requirements in data centers. Solid state hard drives are the current top-of-the-line components here, but while they are blazing fast, they are prohibitively expensive for most, especially considering that they generally feature less storage space than SATA drives.
Memory is, of course, another big piece when assembling a killer system. It used to be that 24 GB of RAM was just for servers, but modern gaming and workhorse business machines can accommodate this fairly easily now, and you'll have to push the limits to 24 GB to have something that is truly special, as 12 and 16 GB systems are fairly commonplace.
Video and Audio
Audio and video is the area where interests diverge most sharply between gamers and other users. Working under the assumption that there is some budget at play, those with less intensive video and audio needs may want to save money in this area and utilize it for upgrades in other areas. But for graphic designers and video editors, and for gamers especially, this is the area where particular attention should be paid. In addition to a large, clear monitor (or, more likely, multiple monitors), gamers and graphics specialists should look into graphics cards that have onboard memory and cooling mechanisms.
The more memory, the better, in general, and gamers who complain of latency in their online gaming environment can make such complaints a thing of the past with a proper video card. Likewise for the audio card, which can support such astounding sounds levels and effects that the computer can double as a home entertainment system.
There are, of course, a number of other considerations that power users must take into account, including the types of drives they'll be adding, support for USB 2.0 and 'Firewire' ports (good for transferring large files), use of multiple video cards for dual monitor support, and a host of others. For those looking to build a top-of-the-line system for their particular needs, however, starting with the components noted above is a good place to start.