Studio XPS 9100, max temperature for Radeon HD 5670?

I've been debugging a 7-year old Studio XPS 9100 to see if I can fix its CPU-related "WHEA_UNCORRECTABLE_ERROR (124)" crashes by tomorrow. The last day for a big sale on a replacement machine if I can't get mine to run reliably, save $569 on a new XPS 8930 Special Edition.

I've done all the low-hanging fruit fixes and will now stress-test the system while monitoring CPU and GPU temps. I need to know the highest safe temperature for my video card. Device Manager says "AMD Radeon HD 5670", but is that enough information to get an answer, or is there somewhere I can look to get the specific make/model? The card itself says "Pegatron HD5670DE" and I believe it came with the 2011 Studio XPS 9100.

Thanks!