Question Desktop PC wont use dedicated GPU but boots ok (with iGPU)

[pao3007]

so I bought old (h67 and i7 2600,+gtx 960) pc, owner said it will not use dGPU, after I DDUd drivers and updated BIOS it started using dGPU, i tried restarting pc, switching psu off to test if it still works and it did, but I left it for week and switched computer cases but now it wont use dGPU, PC will boot with iGPU to windows even if I have gpu plugged in with white led(red led is on when you dont have connected 6pin), gpu is working in another pc, bios doesnt have option to completely turn off iGPU as far as i know.... I tried to reverse BIOS to one version back but didnt work, clearing cmos, ddu again, different gpu....

 

[rgd1101]

make and model of the psu?

 

[pao3007]

(atx) be quiet S6 450w

 

[pao3007]

I dissasembled PC and tried different things and it worked (but in pc case it doesn't) I needed to power on PC without GPU with VGA in motherboard then turn off pc and PSU, switch jumper to reset cmos positiou, unplug VGA, install GPU, switch jumper to normal postion, power on PSU, plug in HDMI and power on PC, after that It worked every time i turned on/off PC.Then I tried breaking it again so I cant boot with gpu and repeated the same process and It worked BUT when I put everything together to PC case it suddenly stopped working....

 

[rgd1101]

if it doesn't work in the case. did you use standoff to the motherboard. might be short somewhere from the case to the motherboard

 

[pao3007]

if it doesn't work in the case. did you use standoff to the motherboard. might be short somewhere from the case to the motherboard

yeah I checked that, but now i know what caused it, bended pin in cpu socket and tight cpu cooler, when I have uninstalled cpu cooler it started working so i installed cooler which has intel stock mounting system and now it works... so I couldnt fix the bended cpu pin well, because it was really bended hard like under other cpu pins... so under higher pressure cpu presses harder against pins and it shored some pins around the bended one....