I recently built my first computer, and today, a day after getting it all up and running, I noticed that the temperatures on my GPU were sometimes - only sometimes - going way up to ~90C while playing games (Planetside 2, Hawken). At other times, it generally stays at a stable 50-60, and idles at around 35.
The card is a Gigabyte GTX 670 OC (The one with three fans), whose settings I have not touched.
Here's a screenshot of GPU-Z while running Kombustor (Furry and Tessy Test, 1080p, No AA). The core clock has, at this point, already been throttled, and is throttled further until it hits about 600MHz and stabilizes at 100C. Below ~85C, it stays at 1200MHz.
Is my card defective? What's going on? I bought this new off eBay, still sealed and such. Am yet to contact the seller.
I reckon the heatsink is not seated properly on the GPU, it's a common problem where vendors are lazy. Your best bet is to RMA or you could take matters into your own hands and attempt to reseat the heatsink yourself with new thermal paste and such.