Just the stock heat plate with the stock fan. I'm SURE my temps. Would be MUCH higher if I ran the same test with furmark. It by far produces the highest temps. I imagine their data is accurate. Not sure if those heatsinks will fit with an AIO cooler or not. It's made for their universal water blocks.
It's a 7950. Stock voltage on my two cards are 1.094v. I modified the bios to boost the power tune to +50. It doesn't need that much, but why not? Then just after burner beta version. Adjusted the core voltage to 1.250 to hit 1200 and memory voltage is stock.
If you are gunna overclock see what you can get out of it without raising the voltage. I don't know what your stock voltage is so you may not need to raise it much to achieve a pretty good overclock. If you are gunna raise voltage do it in SMALL increments and watch core temps and vrm temps closely!
I would assume it outperforms a 7970 clocked at stock speeds. There are two of them in crossfire so obviously together they definitely outperform a single 7970. But yea, I would think one of my cards at 1200/1600 would outperform some 7970's if they were clocked at their stock clocks. Every card performs slightly different but you definitely will see performance gains with overclocking. I would be a little concerned with the vram being naked. Get some heatsinks or modify the stock heatsink like I suggested so you can have some cooling and a fan blowing on the vrm's atleast.