Question [Black Screen] While 2 GPU Connected (Gigabye RTX 3080, Gigabye RTX 3070)

[Shlomi1515]

I Don't understand how ppl using 6,8, and more GPUs at the same time
while im having issue runing my system with 2 GPUs

Each one of the Cards working great as single GPU
while they both plugged in the first time I turn on, Then The PC reboot it self after 5 seconds..
and I stuck with black screen and NO post

after removing 1 GPU the PC does the same. Reboot after 5 second but gives POST

My OLD Rig - using for mining (1 card only)

System: Windows 10 64Bit Updated
CPU: Intel® Core™ i7-3770K Processor
Motherboard: G1.Sniper 3 Intel® Z77 Chipset
GPU1: GeForce RTX™ 3070 GAMING OC 8G
GPU2: GeForce RTX™ 3080 GAMING OC 10G
PSU: VP-800-M-RGB (800W)

PSU Has 2 PCI Power Cables each one gives (6+2 Pins) x2

so my question is why? i dont see the screen while 2 GPU connect at the same time
when i search this question in google I get "yes you can!!" no one mention any conditions

 

[DSzymborski]

Good lord, you shouldn't be running either of these on a cheap, group-regulated PSU of ancient design.

This does not have the power to run both. You only have 720W of +12V power rather than 800W. (Again, because this is a junk PSU). A quality 750W is recommended for the 3080 by itself and a quality 750W will be able to be right at 750W of +12V power.

 

[Shlomi1515]

i dont think its a power issue because I also tried to use a second PSU 500W to the second GPU with 8 pin + 6 pin
and still black screen.... (I hooked Green Cable to Black Cable) to the external PSU to Power UP