My new rig isn't quite the powerhouse that one is, Stealth, but it certainly pumps a lot of frames per second. I myself decided to go for dual-core goodness and you would be amazed at the difference it makes in games, since many newer ones are multithreaded.
Athlon X2 4200
Abit AN8 Ultra mainboard (not the best that money can buy, but close)
TwinX 1024MB PC4400 RAM
80GB ATA disk
200GB SATA disk
XFX GeForce 7800GTX @ approx. 450MHz, since I haven't gotten around to overclocking it yet
Antec TruPower 550W PSU
SB Live 5.1 sound
DVD+/-RW drive
The only new components are the CPU, graphics card and mainboard. I bought the RAM some months ago and it's recently turned out to be faulty, so I'm currently running 1GB single-channel PC2700.
My main reasons for upgrading from my already-pretty-damn-fast machine were noise and creativity. I wanted to build a computer than was more than a dull beige box concealing the computing equivalent of a Mercedes, and I wanted it to be relatively quiet. Note 'relatively', since the old machine had a Delta fan on the CPU pumping about 120CFM at 55dB.
About three months ago I stated my intention to build a Freespace 2-themed computer. That idea died when I actually started work on the machine, because I'm not much of an artist. Not only that, but the structural design of the new machine took up enough time. The case ended up being gloss black, and even that took 3 coats to get right.
As for the structural design...
The case is a CM Stacker. I need this monster to ensure that a) everything fits inside, b) there's room for upgrades, improvements and insane projects, and c) there was no realistic chance of it getting stolen at LAN parties. 'Insane projects' includes an upgrade from castors to tank tracks, since wheeling the thing around is somewhat difficult at the moment.
Truth be told, I've made no major structural alterations to the case. The only change I made was to add a radiator to the top. But it's not just any radiator; it's a Black Ice III Extreme.
I think these things are conventionally placed inside the front of the case, beneath the optical drives and in front of the hard drives. This is not particularly practical with the Stacker because of the armour-plated drive bay mounts, which are too tough to actually cut away to make room for the radiator.
So I bolted the radiator onto the top of the case, on its side with the three fans on the inside surface. The case's top exhaust fan was removed to allow the 1/2" tubes and fan wires to enter the case. The most time-consuming part of this was drilling the holes for the bolts in the top of the Stacker, ie. through 1mm hardened steel, with a Dremel (bought specially for the project). This is pretty much the first time I've played with any type of power tool and definitely the first time I've embarked on a major DIY project, and despite not actually planning anything it all turned out rather well. All the measurements were by eye (the case never saw a ruler) but everything fitted together perfectly. The radiator is secured so firmly it is actually possible to lift the case by it.
So now I've got a big black Stacker with a radiator on top like an off-centre fin. What else does it need? Lights. Two UV and one green. I did actually have a second green neon, but I was working on soldering the pump's power leads and I didn't notice I was leaning on the tube until it broke. After that I decided not to add the lights until everything else was working...
The fan controller from my last machine has one dead channel (I tried running that Delta at full power once, ie. 20W), but I've only got two sets of controllable fans in this one anyway. I cut the switches off the neon power supplies and wired the neons into the controller's power switches, then cut two holes in a drive bay faceplate for the orphaned switches. The two fan groups are wired into the fan controller through these switches, because most of the time I don't need the fans and the controller rheostats don't have an 'off' setting.
The fan groups are:
1) The radiator fans, usually off unless the rad is getting warm,
2) The internal fans (1 on the hard drive bays, 1 on the rear, and 1 Stacker crossflow fan), usually running at low power for the safety of the southbridge,
and the PSU has two fans in it as well. Eight fans on a watercooled machine. It's fairly correct to call this 'hybrid air/water cooling' because it's not a normal example of either.
So yes, Stealth's new machine is undoubtedly faster than mine, but I bet his CPU won't run at room temperature. I've only seen this baby exceed 30 degrees C once (while playing FEAR) but then I turned on the fans...
... which, in case you're wondering, are actually very quiet indeed. Not more than 30dB at full speed.
My housemates estimate I'll be able to push the FSB as high as 275MHz without touching the CPU multiplier and without losing any stability. Further stability is ensured by running Gentoo Linux as my primary OS from now on.