Question System wont boot unless I disconnect the power from the graphics card for some reason

Feb 5, 2020
i7 4470K not overclocked
16 GB DDR3 dual @ 1333MGHz
MSI MS 7821 board
Nvidia GTX 770 4GB
bequiet! 550W

So, last night my system abruptly shut down mid-game and woulnt turn back on when pressing the power button, no fan spin, no LED, no nothing.

I already experienced some weird boot loop earlier this year ( on the same system and all components are from 2014, so each one could pretty much be on their way out.

First obvious choice was the PSU. I fortunately had an almost identical one laying around, so I quickly switched those out. Connected the MB and the CPU power and did a quick test.
System boots, one and done, easy peasy. I then plugged in the rest of the power cables and closed up again. Went back to my desk and hooked up all the periphery.

Pressed the power button aaaand ... nothing. Same as before. Well <Mod Edit>, back to square one.

Opened the PC back up again, checked all connections etc, everything looking good. Did I maybe fry this even older PSU just by powering it once?
Paperclip time. Unplugged all power supply again and shorted the green wire from the MB power cable with one of the grounds. PSU fan starts spinning.
Now I'm curious, was the original PSU actually broken? Paperclip test again and surprise, surprise it still works.

Decide to switch back the PSUs since the original one has cable management and I'm already annoyed enough. Connect the MB power and CPU again for a quick test, boots no problem.
Put everything else in place, close up again, connect to the periphery aaaaand you might guess what did or didnt happen now.

At this point I'm thinking it might be the power switch itself, since both PSUs clearly seem to be working. I removed the cable from the 2 pins on the MB (unplugged GPU power for better access) and shorted the pins with a screwdriver (non-magnetic). System boots normally. Ok, gotta get that power switch from another tower I also have laying around, rewired it, plugged in all power again aaand the new switch doesnt work .....

Now through sheer luck I noticed what seemed to be the deciding factor here. And that is whether or not the GPU power is plugged in (and that is just the power supply mind you, the card is still in the PCI-E slot). So I threw the new switch out the window and put everything back to normal except for the GPU power and voila, we have liftoff.

The only thing left to do was to fully remove the GPU or it will just complain about not being powered on start-up. After that the system switched to Intel integrated graphics and that where I am rn.

So now for my simple question: WTF is going on here??!
How can the GPU power determine whether or not the system boots altogether? Can this be board-related? Would be pretty weird if it was just this one hyper specific thing.
Incidentally, I gave the MB a once-over when the case was open and there are no bulging capacitors, scorch marks or suspicious smells.

Do any of the issues described here point to a specific component? Any additional test I could do (without a multi-meter)?

I feel a bit reluctant to reinvest in a system this old, but if any of you can recommend a GPU on par with the 770 for less than 100 bucks I might consider it.

Thanks for reading and for future advice.
Last edited by a moderator:
The GPU could easily now be defective and loading down the PSU when supplemental power is connected, assuming the PSU is adequate....

You can test that GPU in another rig , or, replace it (if doing any gaming, it is overdue anyway)...
Feb 5, 2020
Hmm, the initial shutdown occurred during heavy load on the GPU.
I just never heard anything about a faulty GPU essentially preventing your PSU from powering other components. Fits the bill though, the system is running without issue since I took out the GPU. Even did some glorious Intel HD Graphics(tm) gaming.

Btw, you'd be surprised how good this 7 year old card still is. I was looking into the <100€ price range and those cards dont even come close.
I settled on a 1650 super. That should give me a decent performance bump and also have ok resell value when I build a new system from scratch.

Thanks for your advice.