I was inspired by Building A Liquid-Cooled MicroATX Gaming Monster and some other thoughts that had been rolling around in my head for a few years and I decided to try to come up with a new build with some unique priorities. I want to create a computer that has only three moving parts (two fans and a pump) that is silent and still performs well in gaming, and is in that MicroATX case. Priorities are, in this order: stability, noise, power, gaming performance, size. Ignore price, upkeep and the difficulty of putting it together. So I have a few questions about parts.
Now, the first question is about the radiator. Because of the limited size of the case, I'm not sure what will fit. The Swiftech MCR-220 and the XSPC RX240 seemed possible, although the one is much thicker than the other. According to the official website I should be able to put in a radiator up to 50mm in thickness so long as the RAM isn't too tall. Does the 50mm include the thickness of the fans, or just the radiator with an assumed 25mm fan thickness?
Second. I'm not sure what fans to use just yet, but assuming I set them to start and stay at 1KRPM, Martin tells me that I should get 0.0479 C/W out of the MCR-220. Subtec likewise estimates a 0.0415 C/W on the RX240, very close. If there are no other fans in the case at all, a maximum of 460W (the total capacity of the PSU) could in worst case scenario get dumped into the loop. 460W * 0.0479 C/W = ~22C. So if the ambient temperature is 95F (35C) and the CPU water block adds ~30C (assumptions based on Martin's WB reviews) from coolant temps, the worst case scenario on the processor would be something like 87C, which on most processors is not melt-down time. So the question is this: is my math right, and could the MCR-220 @ 1KPRM take the full 460W without destabilizing the computer?
Third. Can the fanless PSU function without any case fans?
Fourth. In trying to select a graphics card, I want the best performance/watt possible given the limitations of the PSU. I checked out Tom's Graphics Card Guide: 32 Mid-Range Cards Benchmarked (Page 11) and saw that basically the 6870 and 6850 were unmatched in that regard. According to Radeon HD 6850 & 6870 review the 6850 has a TDP 127W, while the 6870 rings in at 141W. Generally speaking, an Intel Core i7 runs ~95W (AFAICT). According to eXtreme Power Supply Calculator Lite a plausible setup (i7-2600K, 1 SATA drive, etc) with a 6870, the consumption will be 344W. But with the exact same build, replacing the 6870 with two 6850s, the calculator recommends 396W. This may seems like dramatic over-reaching for such a modest power supply, but do these theoretical figures correspond to a real-world plausible setup? It seems unreasonable that a fanless power-supply should be able to run two cards in crossfire! ** Edit: I think I'd like to go with two 7850s or 7870s, given their lowered power demands. See post below.**
Fifth. In terms of fans, what's a good super-low RPM fan these days? I've used the Nexus D12SL-12 before, but I was wondering if there is newer/better that I should look to.
Sixth. There aren't any ATI cards prebuilt with waterblocks, are there? Are there any manufacturers that would be easier/cheaper to switch to water?
Seventh. A lot of folks are seem to be talking about the ASUS Maximus IV Gene-Z, and it looks like that might meet my needs, but a lot of what I'm reading about it is its great overclocking potential. Given the goals of this system (underclocking, not overclocking) is this board overkill? Is there a more suitable, less overclocking-focused motherboard I should be checking out? ** Edit: I think I'd rather either get a Z77 when it comes out, or just go with this board anyway. See post below.**
And just, overall, reality check me on a 460W passive-cooled PSU, 6850 Cross-Fire, single 240mm radiator and no case fans setup.
I'm sure I'll come up with more questions later, but for now, I'd love any insight on any of these questions. Thank you!
And, I've been doing some research. Because of their lower power consumption, I'd rather go with the next gen tech when it comes out. Specifically Souther Islands (Radeon HD 7850/7870) and the Ivy Bridge (next gen Intel Core i7). Those will be coming out over the next 2-3 months, which is the timeframe I was thinking of anyway. Both boast significant reductions in power consumption.
The 7870 is rumored to have a tdp of 120W at full burn. The Ivy Bridge is rumored to have a max tdp of 77W. So the CPU + 2 x the GPU = 317W. If the cooling loop doesn't include the RAM or northbridge or anything but the CPU and the GPUs, then at absolute max I'll only have to deal with 317W. At 1000 RPMs on the thin MCR-220, that would mean a 15.2C air-in/coolant-out delta. at 35C room temps, the coolant will be ~50C during full burn, which should definitely be acceptable.
The only thing that worries me about that is that the case will have absolutely no fans in it (except the two pulling air out of the case through the radiator). Will the RAM and northbridge be able to handle having very little airflow?