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Bios wont boot when unplugged HDMI screen

216 views 1 reply 1 participant last post by  tytanick 
#1 ·
Hi guys i have really strange problem which i am trying to fix for week now.
I cant boot PC unless it has plugged in HDMI screen into Main AMD GPU.
I tried like 50 times now and can say that when i have plugged in screen the PC boots with no problem at all.
But hwne i try to boot the same PC with disconnected screen the PC wont boot.
I am booting from SSD and from USB drive. Both windows, and linux. And both has the same problem, its not OS related !.
As i see this:
when screen is disconnected i dont see usb drive flashing - so it even doesnt start booting.
And when its plugged in to hdmi i see ofcourse flashing ooon usb drive and normally it boots.
So anybody know what is the problem ?
I have the same setups with R9 380 gpus and i dont have this problem.
But now i builded RX480 PC which have the same problem (three of them !)
Also tried to flash different bios to motherboard. Still it isnt helping.
Any idea ?

This sets works fine:
Motherboard: H81 Pro BTC
GPUs: 6x R9 380
PSU: Corsair 1000w

Those sets have problem:
Motherboard: H81 Pro BTC
GPUs: 3x RX480
PSU: 850w Bequiet

And i repead, it boots 100% when i have connected screen.
After it boots, i disconnect hdmi and its working , only booting is problem.
 
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#2 ·
ok i fixed this.
what i did:
i set in motherboard bios "default use onboard vga (intel in my case)"
then booting issue without plugged in screen is solved !.
I have issue that xorg isnt starting and i cant figure out how to make one config that will work on different configurations (1, 2, 5, 6 gpus etc).
Anyway i will propobly stick to headless mode.
In headless mode i had problem when starting claymore in ssh terminal: it throws me seagfault so i thought there must be xorg started .....
But i fixed this - after all user "miner" wasnt been in group video in linux so it didnt had permission for using gpus. But in xorg it had because xorg was started as root and then gave permission for user ....
 
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