Where are you getting the parts from?
CPU: Intel Core i7 4770K. i5 is good as well, but if you're going for the high-end, the i7 might be beneficial in a few cases here and there.
Motherboard: Depends on what you want for features. No need for high-end motherboards for heavy OCing anymore, as OCing since Sandy was more CPU dependent that motherboard dependent. A Maximus VI Extreme, for example, is not needed unless it gives you the features you want.
RAM: You're not going to see any benefits above 1600MHz. So only go for 1866MHz if it's marginally more expensive than 1600MHz. If not, go for 1600MHz, 8GB or 16GB RAM (if you're into running Virtual Machines, or rendering, the 16GB might come in handy).
SSDs: Unless you have a specific throughput target in mind, stick with a single SSD. Windows loading times, general system snappiness, and game loading times will not benefit from SSD RAID0. 256GB SSDs are slightly less expensive than 2x 128GB SSDs from the same family, and you get to save a SATA port, power consumption, and reduce chances of data loss.
Optical drive: Go for a Blu-ray burner, straight away.
This costs about $70 on Amazon.
After you decide for the parts, we'll calculate the PSU wattage you need. Shouldn't be more than 850W-1000W with quite some headroom!
Now for the GPUs and custom waterloop:
GPUs: I'm assuming you want to run a single monitor, though with 2 high-end cards triple monitor and 2560x1440 monitors can be pulled off.
If you want to get flat out the best, 2x GTX Titans, but they're horribly overpriced for what performance gains they net you over 680s, 7970s, and GTX780s.
The next best option is 2xGTX780s, but they also have an elevated price tag at $650 for what performance they offer (62.5% more than GTX770 and HD7970 and around 25% more performance, single card). They also don't respond as well as 79xx cards to OC (not as scalable with OC), and Nvidia has this nasty habit of power limits, which don't hit as hard on AMD cards.
The third best options are 2x 7970 and 2x GTX770. Same price, but the latter costs the same for 2GB of VRAM vs. 3GB on 79xx, not recommended. 4GB cards cost more, and a single GTX770 still can't close the gap to a 7970GHz in demanding scenarios, at stock. Factoring in OC, the 7970GHz pulls ahead,
PARTICULARLY with water-cooling. CrossFire scaling is superior to SLi scaling, so my vote would go to 2x7970 in this case.
You could save some money and go for 7950s, as they have better performance / price, but the 7970s can perform better than the 7950s for more than the "5%" you see thrown around. It can range anywhere between 5-10-20% clock-for-clock, and they pull further away in compute, if you use any GPU compute workloads.
Water loop: I have a water-cooling setup so I will be recommending based on some experience and reading here and there:
1)
Pump: You're looking at the MCP655 as an excellent pump. It's large, quiet, and has a ton of flow. Great pressure as well. At a setting on 1, it's inaudible. At 5, it's pretty audible but still...bearable. I get a difference of 1C between 1 and 5 since I run a low-restriction loop.
2)
Radiator: Water-cooling is more about silence and awesome temps at the same time, than noisy fans and reducing temps as low as possible. That extra drop in temps will probably not get you worthwhile OC headroom, so skip that (water-cooling itself will not get you amazing OC headroom, keep this in mind). You want a medium FPI radiator so that you can use all fan speeds and still get good temps for the fan speed you choose to run at. I got an Alphacool NexXxos 60mm thickness 560mm quad radiator and it does the job admirably. Look at XSPC, Alphacool, Swiftech, etc... for cost-effective radiators, and make sure the radiator is not very high or very low density.
3)
Fans: Gentle Typhoons, great airflow, good pressure, one of the best fans in the world for noise / performance, loved by watercoolers, very robust, very low friction. 120mm and they beat 140mm at noise and airflow. Other fan to consider is the Noctua NF-P12, as these are new, and there is not enough data to compare Typhoons to those Noctuas. They come with directional airflow, which benefits rad performance, but then again, a shroud could get you directional airflow with the Typhoons and, thereby, reduce temperatures (I got a 1-2C reduction in temps by adding 120mm-140mm adaptors that act as shrouds, too).
4)
Waterblocks: Go with an XSPC Raystorm for the CPU waterblock, unbeatable for the performance / price. Low restriction, one of the top CPU waterblocks, and a version costs $50.
4) Do
NOT go for universal GPU waterblocks! I
CAN'T stress this enough! You might say: "Well, I can reuse these across any newer GPUs I buy, they're cheaper too, and I don't have to upgrade my GPU waterblocks with every new GPU purchase". Matter of fact is, VRM temps skyrocket with anything other than the stock air cooler, especially on 79xx cards, and the whole point of water-cooling your GPUs becomes moot, as your VRM temps cause instability at higher OCs!
DO listen to me, I managed to burn a 7970 VRM by not getting enough airflow to a single VRM left alone of the other side of the GPU (memory VRM). The card no longer works, and a VRM replacement was not successful in bringing the card back to life again! Got another card on the way, and a couple of full-cover waterblocks, no more! Pay the price premium. Anyways, you will find that with universal waterblocks, you will have to buy extra VRM heatsinks to keep things cooler, plus extra fans to surround the cards with, and it ends up being as expensive as full-cover waterblocks which cool the cards with
ZERO airflow to the cards themselves!
Not all full-cover waterblocks cool the VRMs with a water channel. Check
this comparison here. Go for EK, Watercool Heatkiller, or AquaComputer AquagrATIx waterblocks if you want to actively cool your 7970 VRMs. I went for Heatkiller waterblocks. All these waterblocks still have lower restriction than some other waterblocks (EK has the lowest). All should be well-built, too.
You'll need some good thermal pads as the ones supplied with the Heatkiller, for example, are mediocre. I got
this for the VRMs, and
this for the VRAM. Make sure the gaps are correct. 1mm can be compressed, but if 0.5mm cannot fill the gap, you'll have to stack (it works). The VRM are 10cm across the card (vertically), so that's why I got the former for the VRMs, ready as 1.0mm. I'll just have to cut it into two and use them for both cards.
5)
Reservoir is a personal choice. I went with a T-line (sort of; keep reading), didn't want to pay the extra for a reservoir. A reservoir makes it easier to bleed bubbles out of your water-loop. The Alphacool NexXxos radiator comes with a fillport / drainport which helps with the filling, emptying, and bubble-bleeding for the loop.
6)
Tubing: Don't go for plastic tubing. They eventually cloud and plasticizer leaks into your loop. You want proper tubing? For flexibility (still) and reliability, go for rubber tubing, the sort that is used for hydraulic purposes. For sick looks, and reliability, go for nickel-plated copper tubing.
7)
Fittings: Compression fittings. Nuff said. Alphacool, Bitspower, etc... do the job admirably.
8)
Coolant: Please do me a favor and don't go for a dyed coolant. It raises temperatures and stains waterblocks. Also leaves residue over time. Distilled water is enough. A killcoil may be added, or CuSO4, whatever works for you. I run pure distilled water with no additives.
For the tubing and fittings ID (Inner Diameter) and OD (Outer Diameter) sizes, things get a bit confusing, so I can help you out with that when you get around to ordering such items.
Now, you're missing something:
some good SOUND! A soundcard is a must along with a pair of good headphones or speakers (cost much more for same quality + no private listening which may bother you or bother others). We will discuss this later, in detail, when you get around to building a good audio setup.
Good luck!
