PC going into start up, instant shut down, restart again cycle

[OakIris]

I have an older PC system that I gave to my partner. The system was built probably in 2010 (can't remember exactly, .) The motherboard is a Gigabyte GA-P35-DS3P, PSU is an Enermax Liberty 620W. It has been working fine since it was built.

Earlier this week she started it up, all the fans came on, and then it abruptly shut down after about 10-20 seconds, restarted, shut down again, etc. No beep codes, not long enough to get to the BIOS screen, let alone to the boot screen. We had had a power outage a few days previously so I immediately thought it must be a power problem. I did all the simple things such as making sure the power cord was fully plugged in, checked the UPS, changed outlets, etc. This made no difference. I tested the voltage of the PSU (24 pin connector and 4 pin 12-V connector) with a multimeter, everything tested out fine. I checked all of the internal cable connections, reseated the memory, still had the same continuous start up/shut down cycle problem.

The system had four sticks of Mushkin XP2-8500 1 GB memory. I removed all but one of the sticks and, voila, system booted up. The motherboard is supposed to be dual channel, but won't start up with 4 sticks, won't start up if there is a stick in slot 1/3 or 2/4 as required for dual channel use. I can put memory in slots 1 & 2 and the system starts up fine, shows 2064 MB of RAM in BIOS. I can't remember the other combos I tried but as far as I can tell, all four sticks are good....

So, is the motherboard on its way out? Could memory slots 3 & 4 have fried somehow without causing any more damage to the mobo? Anything else I should be checking?

Puzzled in Colorado...

Thanks for any assistance!

Holly

[Sick Willie]

I would try clearing CMOS as a first step.

[OakIris]

I would try clearing CMOS as a first step.

I thought about that but didn't do it once I found what I thought was the problem, the memory slots. If I had tried that first and it fixed the power cycling problem, sure would have saved me a lot of testing and fiddling about!

Would you explain why clearing CMOS could help with the memory slot problem? Do you suspect some sort of CMOS corruption so that for some reason the system thinks there is a problem when the two other slots are filled so won't continue into boot up?

In this situation, do I clear the CMOS and then add in the other two sticks of memory, or do I add the memory first and then clear the CMOS? (Or does it matter.....)

Thank you for your help, Sick Willie.

Holly

[Sick Willie]

The behavior you describe as to the apparent shutting down, restarting is common on Intel based boards when the BIOS is searching for a set of parameters that allows the board to boot.

It doesn't really matter whether the memory is installed when you clear CMOS. As a matter of practice, I would clear CMOS, start with one stick of memory and add each additional stick until fully populated.

[EH100501AC]

If you have a spare power supply, try using that.
I'd even pull the motherboard out of the case to see if it's grounding out too.

[OakIris]

I tried clearing the CMOS, that didn't help, in fact made it worse. I was able to run the system with 2 sticks of memory before clearing the CMOS - it was not running in dual channel mode, but at least the system recognized both sticks.

After clearing the CMOS, if I try adding more than one stick the system immediately reverts to the start up/shut down in 20 seconds or so cycle. I tried various combinations, but the system will now only boot up if only one stick is in the first slot. So, apparently I made the problem worse by clearing the CMOS.

EH100501AC - I don't have a spare PSU that will work with this system, just an older model with less power and no SATA power cable capabilities. I can't afford to buy a new PSU "just in case" right now. Do you suspect that the PSU is bad even though it tested out OK?

Also, you mentioned that maybe the mobo was grounding out. What might cause a mobo to start grounding out after it has been working just fine for several years? And if it was grounding out, it wouldn't boot up, would it?

Holly

[Sick Willie]

I still suspect the issue as being CMOS related. Since you've cleared CMOS, you might try loading either BIOS defaults or performance defaults and see what happens.

[OakIris]

I still suspect the issue as being CMOS related. Since you've cleared CMOS, you might try loading either BIOS defaults or performance defaults and see what happens.

I loaded the optimized defaults after clearing the CMOS the first time, then I added in the second stick of memory and the start/stop cycle began again. Should I clear CMOS again and load the fail-safe defaults?


Holly

[Meridian]

Depends. If your RAM is fairly slow then Fail-Safe defaults should be fine. If your RAM is a bit faster, then Standard Defaults (or whatever they call it) is better. Try both, starting with Standard. It's not impossible that the power surge has borked a component, possibly one of the RAM sticks. Of course it may have damaged the m/b instead, hence the fact that you can't run dual-channel. If all four sticks work in channels 1 and 2, but none in 3 or 4, it points to motherboard. Either that, or a default BIOS option has got flipped. Although I would check that your board does actually support that speed of RAM: I had endless issues some years ago with an Asus board because it turned out that model did NOT support 8500 RAM. The result was that sometimes it worked and sometimes it didn't.

M

[Sick Willie]

I loaded the optimized defaults after clearing the CMOS the first time, then I added in the second stick of memory and the start/stop cycle began again. Should I clear CMOS again and load the fail-safe defaults?


Holly

What Meridian said. Fail-safe defaults is as good a place to start as any.