Can you flash a mobo bios if no post?

Replaced a fan on HSF and it ran fine for 3 days (no gaming) when set to auto fan mode but when I changed to PWM mode the system froze up after 2-3 hrs of surfing. I was able to enter bios and change back to auto but I believe while saving it borked and now can't enter Bios. Just led's, and everything spins: HDD, card, fans. Screen is completely black. I've t-shot all components. Has to be the mobo (caps are fine).

Have instructions to flash the bios using a flashdrive. Can I really get a menu and flash the bios using a flashdrive if I have no signal to screen? Never done this. It's a GA-MA785GM-US2H w/ an old phenom II X4 965.


Thanks,

Mac

Have you tried just resetting the CMOS? There should be a jumper down near the bottom of the board somewhere labelled something "Clear cmos."

You shouldn't need to reflash the BIOS if it worked before you replaced the HSF.

Yup, tried that. Haven't removed the battery. What I for the life of me need to find out is: Can I actually get a menu and flash a bios from inserting a flashdrive and pressing power?

Not to tangent away from my #1 question, but to reiterate: I believe the mobo didn't save that last bios change and now the system doesn't find any bios.


Thanks Razorwind. If I can get bios working I'll save myself a lot of work hardware and software wise.

When you say BIOS change, were you adjusting the settings, or actually flashing an updated BIOS onto the board? From your post, it sounds like the former, not the latter.

Unless you were in the middle of flashing a BIOS onto the board when it got corrupted, you shouldn't need to re-flash it. It should just be a matter of resetting the BIOS settings which are stored separately. I would maybe try replacing the CMOS battery and then reset the settings again.

Failing that, this board apparently has two BIOS chips, so if you somehow did manage to corrupt the actual BIOS ROM, it should have a backup it's possible to switch to. I seem to recall it's supposed to switch automatically, but I could be wrong about that. Do you have the manual?

I changed the cpu fan setting under PC Health, back to 'auto' b/c PWM caused a lockup. Thought it saved but then couldn't Post.

I got the orig bios from GB and unzipped unto flashdrive, then booted and it gives me the preliminary Bios screen w/keystroke choices. I press Del for Bios setup but the system just hangs here. Not sure what to try next.

Yeah I've been all over the manual. All 3 methods to flash involve getting past Post. Now that I get something on screen I'm not sure how to progress. Once I'm into Bios I think I can figure out how to save/flash a bios. I've been reading. Just need to try booting it again I guess. It's nervewracking but luckily this is old hardware and I have other hardware. But I'd rather not spend a day swapping the other system into my main case, etc.

Hey thanks for the feedback. Hopefully I'll get this and be able to finish other pc projects. Gonna try Paragon Adaptive Restore to swap an OS from that other system.

Are sure that you've reset the CMOS settings using the jumper? There should be a pair of jumper pins between two of the lower PCI Express slots. You bridge these with something - either an actual jumper, or the end of a screwdriver or similar - for a few seconds, and then remove the jumper, start the system up, and go back into the BIOS settings and configure whatever you need.

You might also try reapplying your thermal grease to the heatsink. Your description of the original problem sounded like overheating, so maybe you just need fresh heatsink grease and to make sure the fan runs.

Changing BIOS settings does not alter the BIOS itself in any way. It only stores some data in a small amount of RAM located on another chip (usually the I/O controller or chipset) that's kept alive by the CMOS battery.

If you're having trouble getting into the BIOS itself, or with system lockups, then you have a hardware problem (either CPU or RAM probably) and not a BIOS problem. DO NOT flash the BIOS with the system in this state. You will almost certainly corrupt it and cause more headache for yourself.


To answer your initial question: yes.
BIOS images have at least two sections: the boot block and the main BIOS (UEFI is similar, but much more modular). The boot block's only job is to get the main BIOS going, and as long as that happens, you never see anything from the its activity. It's the work of the main BIOS that gets you something to see on the monitor.

If the main BIOS fails to start, the boot block is usually able to start a recovery program to attempt to reflash the BIOS. Earlier BIOS's did this blind. They just looked for an image somwhere and hoped for the best. Newer ones have enough code to bring up the video card and get some user input.

Yes did the jumper. Haven't removed the battery. Only got a balck screen until I did the flashdriver w/rev 1.0 (the original). Also re-did the grease.

Boy I'm stumped. I'm certain I can revive the mobo.

Well thanks for the help.

maybe you should have wore a grounding strap? ... just saying

What's the video card and have you swapped? Case speaker attached to read beep codes? Swap out RAM? Need more info.