Weird problem with gpu not posting

[Yourmomm]

New build, 10700kf, msi z490 tomahawk, corsair rm850, 32gb 3600mhz ram, 128gb nvme, gtx 670, phanteks p500a, nzxt kraken x73

 

The build seems to run fine without the GPU (an old gtx 670): it turns on and stays on, with only thr vga led motherboard warning light, as there is no gpu. But I can't tell whether its fine for sure, as this is a 10700kf cpu, so no IGU onboard, to actually see the bios. As soon as I try to install the gtx 670, the build fails to run, just cycling through attempts to post. Yes I'm connecting gpu power correctly, and the monitor to the gpu, and not the motherboard. Led indicators on motherboard are telling me bugger all, they are all lighting in succession (individually), before settling on no vga.

 

I've tried installing the gpu with different cables, into different power supply sockets, and into different pcie sockets. Same problems in every combination....ive even tried to power it from another power supply, in another computer, with same results. Power just refuses to stay on, led warning lights on motherboard, wont post, and cycling power as it keeps trying. As soon as I remove gpu, everything looks fine again....

 

So, obviously a dodgy gpu, right? The thing is, it works perfectly, in the old system I nicked it from (an athlon x2 beast). No problems at all. Nada. I even put it back in its original system, to check it WAS still working, after all this palava. Still works and posts, fine, in that system.

 

I've got no other gpu, to test the new build. PC partpicker says the gtx 670 is compatible with msi z490 tomahawk.

 

FWIW I also tried reinstalling ram, all cpu/atx power connectors, etc, etc, all to no avail.

 

What's going on?!

 

Thanks

[Moonzy]

reset CMOS? possibly faulty new parts, cant tell which

[Yourmomm]

4 minutes ago, Moonzy said:

reset CMOS? possibly faulty new parts, cant tell which

Yeah did that too. No luck. Only faulty part it could be is motherboard, as I've isolated everything else. Motherboard is the only component I bought online, and organising rma will be a nightmare.. . I'm wondering if it's worth just buying a throwaway gpu to check, though...I've heard that sometimes new and old parts just dont like each other very much?

[Moonzy]

Just now, Yourmomm said:

I've heard that sometimes new and old parts just dont like each other very much?

i've used an ATi x550 to diagnose my PC before, as long as it fits, it should be fine