I have two GTX 560ti GPUs that I need to RMA because they crash when running DX11 applications at factory speeds (these are gigabyte overclocked cards 900MHz core and the only way to avert the crash is by under-clocking the core) I purchased them from two different websites, one in March '11 one in June '11 1) is it necessary to send the correct item to the right retailer? i.e. will they have any way to check serial numbers and things 2) is there any way I could identify which one is which?! I have them both, 90% certain I know which GPU I bought second (still has the cover over the DVI port!) not sure about the packaging though... It's a fiddly problem, but I feel I need to get to the bottom of it because they probably get a lot of customers cheekily trying to return old/broken hardware Both are under warranty and I am fully confident I will be able to exchange them for a replacement/refund. My brother uses the same GPU and does not experience the same fault. I suspect it was an issue with earlier models as he purchased his in september '11. Any advice or ideas?