Playing around in the overclocking options for now - 80% of stock frequency is stable (at least in idle) - gonna work my way back up, see how close to 100% I can get and then try actually play some games with my new GPU.
Ohh and surprisingly it didn't crash when I was running some heaven benchmarks with up to 2350mhz (also on stock settings - I tried all 4 preset profiles and they worked fine) earlier but crashed over and over in idle...
This is actually stable. Underclocking the GPU frequency also got it to run stable. Didn't have any crashes when benchmarking so far - only in idle/when doing simple multimedia.