LED is white all the time, when i turn off PC its still white. And they are spinning..
IDK looks like the PSU is OK, but I think there is some hardware problem, under some games load the GPU get's heated and turns off... But if the coolers are spinning there shouldn't be any problem with heating... will the screen return back again if you'll left it like that ?
Do you have another PCI-E full size slot ? Can you unplug the GPU and plug into another PCI-E slot ? it should be right below where GPU is plugged in now, try to test it in games, in same conditions, so that we will now for sure, is the issue in GPU or in motherboard/PCI-E slot connection.
Keep in mind, second full-size PCI-E slot is gonna be most probably PCI-E x8 slot in comparison with main slot which is x16. You can see there are gonna be half less pins inside the slot. However x8 is still ok for your GPU, it'll receive enough bandwidth and wont be less performing overall.