tbh all the setups listed so far are a bit stupid unless you have some specific application in mind for them
Let's go ahead and assume the OP's question was 'the ultimate GAMING computer'. Where to start- CPU. We don't need to delve into extreme edition territory to max out *useful* CPU power for games. At most, I'd say an i7-5930K would be the best option.
For GPU, this could be where we need to go a little overboard, so for this let's say 2 GTX 780s in SLI (780s are near as makes no difference as powerful as a regular Titan). Alternatively, I like the new R9 295x2 :>
Motherboard? An X99 board because we're running a Haswell-E processor. Has to have enough PCI-E lanes (4) for the GPUs, which most do, so really any X99 board will do.
Do we need really high-grade RAM for gaming? Nope. Let's go with a 2x8GB kit of Corsair Vengeance RAM.
If we wanted to go all out with storage, we'd ditch HDDs completely and go with a full-SSD memory array of 5-6 120GB drives. Either that or we could use HDDs and set them up in a RAID configuration of choice- RAID 0 for speed (IIRC). The latter option gives us more space too, but at the cost of the unrivaled speed offered by the SSDs. It'd probably cost half as much as a full SSD array too.
For a PSU, we'd probably go for a 1500W one seeing as those dual 780s will be drawing out power like nobody's business (if put to full use that is).
Cooling would be by H20. Swiftech pump- best pumps IMO (use one in my own rig).
Case- Corsair 900D. Don't question it.
tl;dr this system is still incredibly overkill, not really worth the money for what you get out of it but technically it's the best or therein close to. Sure, there are systems that would outperform this- but I don't think any discernable difference could be noticed.
