Question Motherboard dead? CPU fan starts and stops continuously.

ET

Senior member
Oct 12, 1999
521
33
91
Playing IT for a relative again. He gave me his PC after it stopped working (apparently following a power outage) and only blinks a red light at the front, about once a second. It's an old Core 2 Duo PC. I got the PC from him, and checked it.

What happens is that the moment the power is connected, the CPU fan starts spinning and stopping, about once a second. Connecting a mouse, it also lights on and off. There's still a steady green led on the board.

I connected the motherboard to another PSU, but that didn't change a thing.

I disconnected the GPU, the drives and left one RAM stick. Still the same.

Edit: To make sure the case isn't the problem (his previous case had a stuck power button), I disconnected it from the motherboard. Still the same.

Not a lot left to suspect except the motherboard and CPU. Anything else left to check? Anyone encountered this particular problem?
 
Last edited:

VirtualLarry

No Lifer
Aug 25, 2001
56,229
9,990
126
Ugh. Power Outage on an older board, now it won't power up. Been there, done that. Thankfully, in the few cases for clients (friends and relatives and neighbors), most of the time it was just the PSU, it was either OEM and cheap, and failed due to a surge, or older, and same, failed due to a surge. I think one time it was due to the board frying.

You say that the HDD light blinks once a second? Windows does that for IDE/SATA drives, mostly IDE, mostly on slightly older versions of Windows (pre-Windows-10), if the system contains a CD/DVD drive (polling for disc insertion). That box might actually be booting, just no video output.

The fan stalling, could be due to dust, fried onboard fan controller, or just due to lower temps and fan profile. (Do some older OEM systems shut off the CPU fan when not needed, like modern video cards do?)

Edit: It could just be boot-looping too, and not booting. Do you have a PC Speaker / Beeper connected? Do you get any beeps with the RAM removed? (You should, if CPU/mobo are working.)

Does that board have onboard video? Tried all of the onboard outputs, as well as a GPU?

Tried clearing CMOS? (That's actually the first thing that I'd try, besides swapping the PSU, or doing so after swapping the PSU.) Maybe replace the battery too, that can do wonders for older Core2 rigs that are having boot issues. (Don't ask why, sometimes it just helps. Ask @Fanatical Meat )

Edit: If a known-good working PSU, and a known-good working GPU, and a replacement CMOS battery and subsequent CMOS clear operation doesn't help, I'd chalk it up to "bad board" or even "bad CPU" (especially if you don't get any beeps with a beeper attached, and no RAM installed).

Time to start upgrade planning, if that's the case. (Ryzen R5 1600 CPUs are getting cheap, approaching $100, and sometimes you can get open-box/refurb boards for $50 or so for a B350 or even an X370 ATX board if you keep your eyes open for them at Newegg. $100 for a kit of decent fast 16GB DDR4, and you're golden.)
 
Last edited:

Ketchup

Elite Member
Sep 1, 2002
14,545
236
106
Agree with VL, recommend checking the video card first. And at least with a build that old, it won't cost much to replace the vitals with something much better but still not top teir if it does turn out to be a dead board.

Short story: I have had a few people bring me computers with failing power supplies, but the funniest/ weirdest one was a lady with a lightning hit that took out the south bridge of the motherboard. Due to the generation of the computer, it could never be connected to the internet again, but she had some games on it so gave it to her daughter as a play computer.