The ASUS Radeon 7870 w/DirectCU II has been reviewed here at SPCR
The DirectCU II on the HD7950 is a dual-slot cooler, so could perform a lot better.
But I still think it would perform silent (but still not unhearable) when idling and doing the vacuum-cleaner under load. Without any measurements by SPCR it wouldn't be the way to go.
But if I would buy the product, I will try it with the stock cooler and stress it and publish my results (although they aren't measurements).
I've seen the results from the GTX 680 on SPCR as well, it looks a lot more like the cooler of the HD7950 (dual slot). But I'm not impressed with the results. 85 degrees for GPU and 112 for VRM with a sound level of 17~18 dB is not good enough (for me), and there hasn't even been spoken about OC...
With another version of the HR03 (the HR03 plus serie), I've stressed the 8800GTS (old card, I know, but it's about heat-dissipation anyway), and hit about 65 degrees max for the GPU when overclocking about 30%~40% for CPU and GPU. AND with an acceptable sound level (the rig I now have is hearable, but silent). The fan on the GPU-cooler did somewhere around 800RPM, I think.
There are no real performance advantage by having a high end SSD compared to a mainstream SSD
You got me interested. My choice for the Samsung 840 pro (else it would be the Samsung 830) is based on the 20%~25% extra performance it does in tests. But, the results are based on benchmarks, not in games/programs/boot-ups or whatsoever. Do you have any reference to a test which proves the advantage in more realistic environments instead of (theoretical) benchmarks?
About the 2nd GPU just above the PSU:
Don't think this is a good idea, you are going to move hot air through the PSU, making the fan go faster to compensate: sort of using a "hotbox" PSU configuration.
Yes, but my alternative is mounting the card higher and blowing the hot air up, so making a lot of turbulence, or blowing it down, right to the PSU anyway.
When I am at the point to putting the 2nd GPU in the system, I will try several set-ups to see what option is best.
About the capacity of the PSU:
I think this could be a problem, not when using one GPU, even with overclocking, but in crossfire this could be a point.
But there isn't a silent alternative. The only PSU powerful enough (tested by SPCR) is the Corsais AX850. But that's producing an unacceptable 24dB at 600-700 watts, and than I haven't watched the hot-box performance (and keeping in mind the second card will be close to the PSU, that would be more realistic).
My plan for now is to make the single-GPU configuration and overclock it to the max, stress it and watch the power consumption.
I could place another PSU to even the load, and with an adapter to duplicate/simulate to "motherboard = on" signal, it would work. I think I have a Nexus value 430 somewhere not used now, so that's the to go with by then. It's not the best solution, because I want to show the world that there is no need for exotic solutions to make a silent and yet powerful system, but maybe that's a bit too optimistic. The time will tell us...
Maybe a cheaper Nexus is an option, but the last five years there hasn't been much progress in PSU's (regarding to need of power), so when I buy a silent one now, it's keeping it's value after five years. And that's good enough for me. (about costs: the price doesn't make the costs, it's the write off you will pay finally)
About RAM: I think I'll try it anyway. It'll cost about 3% of the price of the total system, and maybe it's not making any difference, I could overclock with it and I've never seriously done that.