OK I got an ASrock H81 Pro BTC 2.0 with 6 PCI-e slots to build a mining rig. It is commonly used for this purpose. I installed an RX 470 GPU using a powered USB riser and so far so good. The 2nd GPU would not get recognized on a riser so I changed riser hardware, tried another PCI-e slot and still no go. I then installed the 2nd GPU in the 16X PCI-e slot on the MB and got an error message during BIOS startup asking me to plug in one of the 2 molex 12V connectors that are present to supplement the PCI-e power draw. It also gave the option of just pressing a key and continuing with the boot which I did and the system did not recognize the GPU installed on the 16X PCI-e slot so I rebooted and saw the message again. This time I powered down and installed the 12V molex as requested but when I powered back up again the CPU fan ran for about 1 second and nothing happened. I turned off the power but it was too late, I could smell a slight whiff of fried circuits and it never would turn on again even with the molex removed. I tried a 2nd power supply with no success so I think the MB is dead.
Also I had been running the same MB for over a day with only the one GPU running on the PCI-e riser with no issues whatsoever, so it wasn't an initial startup issue or anything shorting out.
My question is how in the world can this happen? I don't understand it. The BIOS startup message clearly instructed me to do this so I assumed it would be safe. The user manual says to use the molex when 3 graphics cards are being used but I was only using 1 on the MB and the 2nd GPU was on a powered USB riser. The GPUs get most of their power from their VGA power cable connected so the amount of power needed directly from the MB should be 50 watts or less.
Unfortunately this is the 2nd time I did this, I fried another MB in a similar fashion by connecting the molex on the MB to supplement the GPU power requirements. This 2nd time I was very gun shy on connecting the molex due to my prior experience but since the BIOS boot up asked for it to be done I went ahead and did it - big mistake.
My ongoing assumption (obviously false) has been that even if power is available such as provided by the molex unless it is used or shorted it does no harm to any other circuits.
Any ideas or theories on how this could have happened? I'll never do it again I can assure you but still don't understand why it occurred.
Also I had been running the same MB for over a day with only the one GPU running on the PCI-e riser with no issues whatsoever, so it wasn't an initial startup issue or anything shorting out.
My question is how in the world can this happen? I don't understand it. The BIOS startup message clearly instructed me to do this so I assumed it would be safe. The user manual says to use the molex when 3 graphics cards are being used but I was only using 1 on the MB and the 2nd GPU was on a powered USB riser. The GPUs get most of their power from their VGA power cable connected so the amount of power needed directly from the MB should be 50 watts or less.
Unfortunately this is the 2nd time I did this, I fried another MB in a similar fashion by connecting the molex on the MB to supplement the GPU power requirements. This 2nd time I was very gun shy on connecting the molex due to my prior experience but since the BIOS boot up asked for it to be done I went ahead and did it - big mistake.
My ongoing assumption (obviously false) has been that even if power is available such as provided by the molex unless it is used or shorted it does no harm to any other circuits.
Any ideas or theories on how this could have happened? I'll never do it again I can assure you but still don't understand why it occurred.
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