BIOS keeps reseting on Gigabyte mobo

[Ken90630]

Hey, All,

Two years ago I replaced the mobo, CPU and RAM in a friend's PC. All has been fine until yesterday. The mobo is a Gigabyte GA-B85-HD3 (Socket H3). The CPU is an Intel I5 (LGA 1150, Haswell).

Each time the PC is powered down for any length of time and started back up, a message comes up during boot-up saying, "BIOS has been reset." There are then 3 options to choose from re how to proceed. I can go ahead and boot into Windows, but of course the date and clock are all out of whack (showing December 2012, etc.).

I don't get the BIOS reset message if I just do a restart. It's only if I power down for a few minutes or overnight and then power up. I've Googled the problem, but there doesn't seem to be anyone else having this issue.

My first thought is the battery on the mobo, but this board is only two years old and I've never seen a mobo battery go bad that soon.

Any ideas, anyone?

PS: I also posted this in the Motherboard forum. If a mod wants to delete one of the postings, feel free. I just wasn't sure which one to post in. *shrug*

 

[VirtualLarry]

Yeah, that sounds like a CMOS battery problem.

When you say "power off", do you mean shut off the power by turning off the switch on the back of the PSU, or unplugging it, or using a power strip?

Because, normally, ATX PSUs supply +5Vsb power to the mobo, even when in the ATX soft-off state. That power is what normally supplies the power to the CMOS settings, the battery only comes into play when the PC is unplugged or shut completely off.

Your PSU may have a failing +5Vsb line. Especially if it's old, this can happen.

Does the PC take a while to power on, sometimes, after you hit the power button, or does it power on immediately to BIOS POST screen?

If it takes a while, that's another indication that the PSU is failing.

 

[Ken90630]

Thanks, Larry. I replied in the Motherboard forum (to my duplicate posting) before I saw your reply here.

As I said in that reply, yeah, the problem appears to have been a dead battery. I replaced it and have done a couple unplug-the-PC-and-then-power-it-back-up cycles, and it seems to be working okay. No more BIOS reset message.

I agree with what you said about the PSU though. You're exactly right, and if it's just starting to go bad, the problem could be intermittent and not show up again immediately. If the problem returns, that'll be where I'll look next. It's a high quality Seasonic, and only about two years old, so I'd be surprised if it's the culprit. Anything's possible though.

To answer your quesiton, I'm not aware of any delayed response time after the PC is turned on -- it seems to go right to the post screen. Then again, this is my friend's PC and I just started working on it yesterday. It hasn't acted up, in that way, for me though.

Thanks.

 

[Ken90630]

Addendum: Just for the heck of it, I dug out my PSU tester this morning and hooked it up to the PSU. All the voltages are there as they should be, except for the old -5V (which isn't used anyway).

Of course, this tester just measures the PSU's output without being under load, so it's always possible that the PSU could test okay and then fail under load. But given that the +5V line is used to supply power to the CMOS even when the computer is off, and thus not with the PSU under load, I'm going to assume the PSU is fine since the tester says it is.

BTW, do you know of any practical way to test a PSU under load? Without risking frying something, that is? I have a multimeter and could stick a probe into pins on connectors, but I'd be afraid of blowing something up. I don't need to know for this particular case, but it might be handy in the future if the need ever arises.