RAID 0 basically doubles your speed, and since you have a huge budget, two 36 or 74 GB 10K SATAs (WD makes good ones here, my dad just got two for RAID 0, no info on performance yet). However, it may require a really good RAID controller, many onboard ones were crappy, OS dependant controllers that were still mostly software RAID (on the driver level). I'm unsure about modern ones.
As for the unconventional cooling, I suggest water cooling or thermoelectric using a peltier and a heat sink/quiet fan. Peltiers use A LOT of power though, I believe typically they tell you to get one that uses no less than 200 watts. Speaking of power, you should check out the Super Flower/TTGI power supplies which are on sale at Directron.com right now. I got a really nice 520 watt for $50 after shipping. TTGI/SF is known for high quality PSUs (stable voltage under high load, etc) but at a really good price (PSUs have HUGE markups on them). Not sure if you need a power supply or not though, and the SFs, at least the one I got, have no SATA support. Antec just came out with a ($160!) modular power supply, like a 480 or something (which you supposedly need for the 6800s, at least the Ultra I think), all modular connectors, SATA support, etc.
Now...water cooling, there's something I know quite a bit about, as I am currently building my own water cooling system and have done a lot of research. I'm not sure how familiar you are with the components in a water cooling system, so I'll explain it from the bottom up, for everyone's sake. I don't recommend buying a kit, generally they offer poor performance, are expensive and just not as fun.
Waterblock: Also called heat exchanger, it's basically a heat sink that draws heat away from the CPU and into the water. Anything from a simple spiral design such as
this to fins, or
pins such as that Swiftech block there. Typically you want something that has cool water flowing right over the die and warm water removed near the edges, like what I've shown here. I'd checkout
DangerDen and
D-Tek Customs for waterblocks, also be sure to check Froogle and other shopping search engines. Waterblocks in particular that I recommend are the DangerDen blocks, but most especially the
Swiftech MCW6000 series, which is one of the best blocks on the market (like over 200 pins on that internal design!), and only $40 USD, compared to the $50 or $60 DangerDen models. Either of those two places should have blocks for any socket you could want, in fact I the Swiftech block has mounting brackets for the K7, K8 and P4. Oh, and get a copper block, the aluminum ones are no where near as good (seeing as how copper's heat conduction is 400 w/mK and aluminum is like 250 w/mK). Don't buy into the expensive silver blocks, they offer little to no performance increase, and are many times as expensive. Oh, Zalman does have some really nice blocks which are gold plated, which is awesome since it'll pretty much never corrode.
Pump: Uh, yeah, a pump. Either a 12 VDC or 110-120 VAC pump. If you go AC, you'll want a relay which can turn the pump on and off when your computer starts. They take up a PCI slot (well, a case slot at least) and cost like $20. For less than a buck you can pickup a 9 or 12 VDC relay whose contacts are rated up to like 120 VAC and 3 amps at a place like All Electronics or various other surplus stores, and build the circuit yourself. You'll probably want an easy to mount AC socket near your power supply, which can then connect to the pump. This may be a bit of a trick if you're in Canada, I guess you can check Canadian electronics stores for these. Or you could drill a hole, but that's not very professional now is it. Now other than that, you need to be concerned with two parts of a pump's specifications: flow rate and max head. Flow rate is...flow rate. You'll want one that does at least a good 200-300 gallons per hour, and one with a max head of a good 5 or 6 feet. Max head is how high it can pump until it cannot overcome gravity. Your average water cooling setup, if done right, shouldn't ever go over two or three feet. DangerDen and D-Tek should have some good pumps, you can also go with a cheapo aquarium pump like the Via Aqua 1300, a 370 GPH pump that costs about $20 at the right retailer. Build quality seems inconsistent; some people say they die in two weeks, some people have had them running for two years. A little noisy until you fix the impeller to the shaft (which is the anti-clog mechanism, something not needed in a WC setup). Procooling.com has an article on this. But with your budget, I'd just go with a high end Swiftech 12 VDC pump. Those things are like, totally quiet.
Radiator: So now you need something to remove the heat from the water. Some are mounted outside the case, some inside. I prefer inside myself, much tidier and way less ugly and bulky. You'll want one that's at least 120mm in size, people usually mount them in front of their front case intake, which of course has to be 120mm for it to work well. 80mm radiators are pretty crappy, the 120mms just get you SO much more surface area. You can buy an expensive like, $70 dollar radiator or buy a heater core from a car. Heater cores are under the dash and engine coolant is pumped through them to heat the cabin. They work so well for WC radiators that places like D-Tek are starting to sell them for around $20. The 88 (I think that's the year) Chevy Chevelle heater core is supposed to be great for water cooling.
Reservoir/t-line: Reservoirs usually mount in a 5.25" or 3.5" bay or anywhere else in the case (some are cylindrical), and make filling and bleeding easy. Filling is, well, filling the water, bleeding is bleeding the air out of the water. Reservoirs make nice air traps for this. They're bulky, kind of expensive and just annoying. I like t-lines myself. Basically, it's a T connector which you have in your loop. You fill the loop through the top of the T, and let the air flow bubble up out of that point. Then you cap it. A t-line or res MUST be at the highest point in your loop otherwise it won't bleed properly.
Tubing: Yeah, you need tubing. You can get super expensive Tygon brand tubing, which is a kind of very flexible PVC formula tubing that costs about $3 a foot, or the cheaper ClearFlex 60 PVC which is the same formula for only about $0.60 a foot. Check out
McMaster-Carr for both kinds of tubing. Unfortunately I can't link you direct, so just search for "chemical pvc tubing" and you should find both the ClearFlex 60 and the Tygon on the chemical tubings page. The ClearFlex is the generic, unnamed PVC chemical tubing on the left side of the page. It even says ClearFlex 60 on it, I have some in my basement. McMaster-Carr should also have about any type of tube fitting or hose clamp you should ever want. Oh yeah, get some worm drive hose clamps too. Any other kind are pretty crappy. Once those are on and tight, the tube will
never come off.
Water: Yeah, you need water. Distilled water, and nothing else. Costs like a buck at a grocery store. Read the label; the more distilling/purifying processes it has gone through, the better. But don't sweat it if they don't have some that isn't super pure. You need an anti-corrosive and an anti-algae agent, some water additives do both. Some people like ethylene glycol (antifreeze), but it's very viscous and isn't very good as a coolant. D-Tek, DangerDen and other places should have decent water additives. FluidXP is a pretty good one, I think Swiftech makes one too. Try and find one that stops corrosion and kills algae, if not then get two seperate ones. Find some Flourinet if you can, it's a coolant used in super cooling systems in Crays and such...It's anti-corrosive and, I think anti-algae. But that stuff is like, expensive. But you might invest in it anyway. See if you can find places that recycle it (yes, it can be recycled very well). Also, if you choose to get a UV reactive dye, be sure to read the instructions. Usually it's like 1 part dye to 2000 parts water, you want like one or two drops in your whole system. I'd start with like half a drop, let it mix, test it and add more half drops (or just small drops, whatever) until it has the desired glow. Too much kills the UV effect. Oh! No matter what,
do not use household chemicals such as bleach, ammonia, alcohols, etc for water additives. Besides killing the thermal properties of water, it'll probably throw the pH of your water WAY off and corrode **** in just a few hours.
Oh, one note...don't use dissimilar metals in a water loop, as you may be aware, you'll get galvanic reactions. Although the metals won't touch, and even with an anti-corrosive it still happens. If you get a copper waterblock, make sure the radiator has copper or brass tubing (copper preferably, brass is **** for heat conduction). Try to keep any tube fittings plastic or brass. Though if you have like, a gold plated Zalman block, that's not a big deal since gold isn't that susceptible to galvanic reactions.
Did I cover everything? Gee, I think I did. Not sure why I made such a huge post...Guess I just felt like talking about water cooling. Also check out
this article for more on water chemistry.
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Bassoon, n. A brazen instrument into which a fool blows out his brains.