i got it attached...... this thread is oooooooooold.
Anyways, I got it on there after some time of postponing.
I will attest to the performance, not a good as the 560ti furmark. I cannot actually fully attest to the furmark results... here is why.
You need to cool the vrms I had a msi 7950, and I did not really want to invest in more things to cool the vrms.
My card would fail because the vrms hit massively high temps. If I were to guess on the max temp on the core (as the vrms failed my card in furmark before max temps were hit on the core), would be about 65c (i would hit 60c core before the vrms hit like 100c+ and failed) but I could guess on the curve and I would say if it were given another 10 minutes it would hit 65c.
So TL;DR, max current furmark core temp on twin frozr 7950 at 1100 core/1250 mem/ 1100 voltage is 80c. With the 620 it would (guess) hit about 65.