I gave my mom an old PC and there are two external video cards. (The MB has onboard video too.)
Video card #1: when coming from a cold boot there’s a ~50% chance the video card will not get detected and the computer will switch to onboard video instead. There are never issues with resuming from sleep or rebooting. Only cold booting shows problems.
Video card #2: the monitor just seems to blank out sometimes. PC is running fine. Monitor is not “off”. (The light is blue, never yellow.) I haven’t tested a whole lot, but it seems that going into/out of sleep mode via the power button on the PC case fixes the issue.
Video card #1 is newer and therefore better and more powerful. Both cards are nVidia. Both cards are old. I can list the model numbers if you need them.
Diagnosis? Could it be the power supply is too weak/old to power them? It says on the box it’s rated at 400 watts. I dunno.
That’s low for some cards. You should be able to look that up based on the model number printed on the video cards.
I’d also suggest that it might be the motherboard, or PORT on the motherboard. Take the cards out, blow the port out well with canned air or similar. Check the cards for nicks/scratches and whatnot on the copper connectors where it plugs into the port.
Using old hardware can be a crap shoot sometimes. Things that will get you are dust causing poor connections, unknown hardware status, unknown cable status, and loss of configuration if settings are kept with a now old CMOS battery or similar.
What @TheSHEEEP said, you need a way to isolate good/bad status. Typically you take the unknown item like a video card and put it into a working system to test good/bad status.
I guess a follow up question would be, does it work with the onboard video?
First thing I’d try is to remove card #2 and reseat and check connections on card 1. If it doesn’t improve, try the video cable that had been connected to card 2.
Older systems will typically have less efficient components, including cards. Even if it was originally fine, it’s entirely possible the PSU isn’t up to snuff anymore due to degradation, as well. Hopefully the testing process will tell you it’s not the motherboard.
I don’t have a lot of extra hardware lying around to swap. I do have another old unused PC, but the power supply is the original that came with it, so likely is less than the 400w I have now. I used to work at a PC repair shop, and they’ll likely have some used PSUs. I could go there.
How many amps can the power supply deliver on the 12v rail? How many does the video card require? The latter should be listed in the card’s specs or system requirements. The former should be on a spec sheet or maybe a label on the PSU.
