Im trying to troubleshoot an issue at the moment that involves my msi lightning 7970 and my cooler master silent pro hybrid 850. When I install the gpu into pcie lane, the pc will not boot but it will boot if i put my old gts 250 back in. I rmad the msi card and the replacement worked for two days until the same problem came back. The msi card initially worked great for 2 months. After scouring countless forums for answers, ive come up with little new input. I get that its either A:another bad gpu (which ppl say is highly unlikely) or B: the psu is failing under the additional load (which ppl also say is highly unlikely if it was working before...)
So, can I test for this phantom amp draw? Could I install the card and check voltage off the 12v rail? Can I test for it at all with a simple multimeter? I dont want to rma the psu if i dont have to as that will put me out of a pc for a month.
Reading amperage with a VOM meter would be tricky. You'd have to insert the meter between all the +12v points at the card's pwr connector and all the non-black wires of the 2 PCIe power cables. (and there are 7 of them on your card) And the meter would have to be able to withstand up to 23A. That would be a tedious and cumbersome project. Without lab instruments, I can't think of an easier way to do it with a simple VOM meter.
You can check the voltage, however, while the card is in use by probing any pair of the + and - wires at the card's power connector. That might tell you if the PSU is over-volting the card.
Can you get a brave friend to let you test the card on his machine?