The XFX card is in the top slot, when I tried it in the bottom slot windows acted as if I had no drivers. even when it was the only GPU in there I thought it used to run hot, My case is medium size I guess, the CPU temps are fine 35c-40c, I would not think my case would be an issue, it does not have great air flow, but with the side case off its alright. It does not really "shutdown" it more just turns off instantly. I think it is a PSU issue to be honest.
The CPU thermal threshold powering down isn't a shutdown, it just turns the PC off. I should have been more specific
It doesn't sound like that is what's going on here though...In your first post you mentioned the Sapphire card won't work correctly in the top slot and now you've said the XFX card won't work in the lower slot. What driver version are you using? And are you getting the drivers from Sapphire/XFX or are you just running the ATI ones and CCC? This very well could all be PSU related but I feel like there are too many other funky things going on for me to give up on troubleshooting!