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Asus P3B-F Hardware Monitor Error (voltage)

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First post, by GuyTechie

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Just got a Asus P3B-F 440BX motherboard from a seller on Ebay. When I boot it up, I get a Hardware Monitor Error. I go into the BIOS and I see a red text for -5V (says it's actually -6.14v).

I'm using a new Corsair CX750M. I tried a different PSU (another CX750M) - same thing.

After some Googling, this guy seems to have the same problem, but was told to just ignore it. That doesn't seem right...
http://www.pcreview.co.uk/threads/p3b-f-bios- … -error.3831759/

Anyone else seen this issue before?

Edit - more details: I got this with the original bios (1004). I also updated to the newest "beta" firmware (1008f). Same thing on both.

Edit - more Googling and I found this:
http://forums.anandtech.com/showthread.php?t=21443

Seems that modern PSUs no longer have a -5V rail, so the hardware monitor freaks out and just displays -6.14v when it's actually floating. I confirmed by looking at the specs of my PSUs.

I'm still not feeling all that good about it. I wonder if I should look for an older PSU. Dang... that sounds like a bad idea as soon as I said it...

It is annoying the motherboard just hangs there until you hit F1 to continue though.

Reply 1 of 6, by luckybob

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its fine. -5 was rarely used, save for a choice few sound/midi cards. If you care enough, you can make your own -5v supply rail. Or put a resister fro the -5v line to ground. or just ignore it.

I'd just ignore it, or turn off reporting in bios.

It is a mistake to think you can solve any major problems just with potatoes.

Reply 2 of 6, by archsan

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Yeah, I've got something like -13.4567 V myself. No big deal if you aren't using very old sound cards like Roland LAPC-I for example.

Btw, what CPU have you got with it? Tried a 133 FSB one?

"Any sufficiently advanced technology is indistinguishable from magic."—Arthur C. Clarke
"No way. Installing the drivers on these things always gives me a headache."—Guybrush Threepwood (on cutting-edge voodoo technology)

Reply 3 of 6, by GuyTechie

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I only have a PII-266 (that came with the mobo) - that uses FSB 66MHz and a PIII-650 - FSB 100 MHz.

What I'm surprised about though is the PII-266 has a small heatsink and fan (retail), but the PIII-650 has a large but passive heatsink. While idling in the BIOS, the CPU temps according to the hardware monitor went up to 68C! I quickly plugged in a 120 mm fan to the CPU fan header and it went down, but the hardware monitor then warned me about the fan speed being too low (1400 RPMs) - I guess doesn't know 120 mm fans doesn't spin all that fast, 🤣.

I have a SB 16 (CT2230) I plan on using. Does that need a -5V rail?

I found out you can set the hardware monitor to ignore certain things including the -5V rail, so I did.

Thanks for the replies!

Reply 4 of 6, by Arctic

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archsan wrote:

Yeah, I've got something like -13.4567 V myself. No big deal if you aren't using very old sound cards like Roland LAPC-I for example.

Btw, what CPU have you got with it? Tried a 133 FSB one?

I have the same problem. I get freaky voltage readings on my P2B of like +13.6v.
That is why I immediately stopped using it. Could that mean that our boards need new caps?
Because I think my power supply is still fine.

Overvolting your components can (and probably would) damage them.

Reply 5 of 6, by archsan

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GuyTechie wrote:

I only have a PII-266 (that came with the mobo) - that uses FSB 66MHz and a PIII-650 - FSB 100 MHz.

What I'm surprised about though is the PII-266 has a small heatsink and fan (retail), but the PIII-650 has a large but passive heatsink. While idling in the BIOS, the CPU temps according to the hardware monitor went up to 68C! I quickly plugged in a 120 mm fan to the CPU fan header and it went down, but the hardware monitor then warned me about the fan speed being too low (1400 RPMs) - I guess doesn't know 120 mm fans doesn't spin all that fast, 🤣.

OK, I've got a 800EB that my board sometimes won't POST with, even though I set it at 6x100 (probably another issue). Though when it has booted successfully 6x133 seems to run just fine afterward. Still I think it's safest to stay with native 100 FSB Coppermine chips.

I have a SB 16 (CT2230) I plan on using. Does that need a -5V rail?

Nope. The Mystery -5V Rail

Arctic wrote:
I have the same problem. I get freaky voltage readings on my P2B of like +13.6v. That is why I immediately stopped using it. Cou […]
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I have the same problem. I get freaky voltage readings on my P2B of like +13.6v.
That is why I immediately stopped using it. Could that mean that our boards need new caps?
Because I think my power supply is still fine.

Overvolting your components can (and probably would) damage them.

Hmm, what's that +13.6V on? +12V?

Mine only has that random reading on what supposed to be -5V though, the other numbers are fine (the better the PSU the tighter the values of course). Since the board and components don't use -5V there should be no problem, as long as the PSU is good.

"Any sufficiently advanced technology is indistinguishable from magic."—Arthur C. Clarke
"No way. Installing the drivers on these things always gives me a headache."—Guybrush Threepwood (on cutting-edge voodoo technology)

Reply 6 of 6, by SPBHM

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you can set the bios to ignore the -5v error, that's normal.
I have it on my P2B since I used a newer PSU.

also in general you can't always trust MB reading all that much, you need to measure it with a voltmeter or something.

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