video tdr failure on rx480

Hi, I need some tips how to get my card going again.
I flashed my card with atiflash and modded my bios with Polariseditor. I changed the timings to 1750/2000 and memory clock to 2235 and it was stable for some hours and then crashed. after it crashed i didn't have time to reflash it again. so I shutdown the rig and flipped the Vbios switch to "gaming mode" a bios that i haven't modded. And it worked great for 2 days but after that it crashed again. then when i set it as a display card i only came to windows logging then it crashes and says it's a error "video tdr failure (atikmpag.sys). so I reinstalled windows and it worked good until I installed the drivers and then gets the same message. but if i install another card (with modded bios) as a display card its works again.

Things i tried:
changed risers
installed newer and older drivers
install the card direct on the mobo.
run linux (pimpOS)
flash original bios with vbios switch in "silent mode" (bios i originally flashed)

My setup:
Msi z97 gaming 5
Intel celeron g1840
4 gb of ram
Evga gq 1000w
sapphire nitro+ RX480 8gb (Samsung memory) x3
win 10/PimpOs
sg-miner/claymore

I hope you guys have some tips or I think I need to RMA it