MSI 745 Users, Take Notice!

[Gurm]

Ok, so after a year of owning this board/chip combo (MSI 745 and Athlon XP 1800+), on the eve of getting rid of it, I've FINALLY found the cause of the "doesn't want to stay at 133(266)Mhz FSB" problems.

Are you ready for this? You're gonna love it.

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The fan. Yeah, this board apparently has a problem with the fan. It's picky about the information it's getting from the CPU fan, and if it doesn't get the right information, it won't boot. HOW ****ED UP IS THAT?

I mean, here's the deal:

It was running fine at 133, with my Volcano 9. I pull the Volcano 9, and slap on a smaller, quieter HSF.

Oops... won't come up. Diagnostic LED's say it's hanging on memory detection. Huh???

So I try different BIOSes, clearing the BIOS, everything. Nothing helps, it just won't go to 133!

So I think maybe it's heat... slap the Volcano back on and it works.

ARGH!

Then I notice something. The Volcano has a regular fan lead... which is plugged into a splitter. Red and black go to a regular molex +5V plug, and yellow goes to the CPU fan header.

Then it hits me - that's the secret. So I take the Volcano out, slap the other fan back on, but this time using the jumper plug... and it works. Flawlessly.

ARGH!

- Gurm

[Wombat]

Hmmm. I'm running my Volcano off the MB. I can't wait to get home and see if this fixes my weird little problem.

[Wulfman]

gurm, nothing new there.

happened with my system too. do you know how I found the problem?

I read the error message.

it popped up while posting (system fan error or failing or something along the line).

mfg
wulfman

[bsdgeek]

While asking the obvious, is there an option for "CPU Protect if fan fail" or some such engrish?

[Technoid]

Fan detect is toggleable

[GNEP]

I was going to say - I have run it fine with no fan on at all (watercooling). When booting it will say "CPU Fan Fail" or something similar and ask you if you want to continue booting.

You can though turn the checking off in the BIOS - then it boots without testing for the fan.

This IIRC was using BIOS v1.6

So it may have been that something else with the fan was causing problems here...

[Gurm]

Erm, yeah actually I found that spot. I'll have to try turning it off, hadn't even thought of that! D'oh!

(Just didn't know that's what it was for!)

But seriously, I wonder what exactly they're checking?

And you'd think it would do something more sensible than just hanging on the memory detect phase!

- Gurm

[Jon P. Inghram]

It's probably just an "idiot proofing" feature, to help keep someone from powering up the system without a working CPU heatsink and/or fan.

[Gurm]

Yah. But why does it think that my fan is just fine for 100Mhz, but not for 133Mhz?

That's what drives me nutty. That's what made it so hard to pin down!

- Gurm

[az]

It divides the fan speed through memory bus speed?

AZ

[Gurm]

Seriously, it must!

But honestly, I just don't know. I mean, the yellow wire is speed - and that wire goes to the same header regardless.

The only thing DIFFERENT right now is that I'm using the black & red wires (ground/+5v) from a molex instead of from the fan header.

Is the fan header not powerful enough, or something? It's tres bizarre.

[Wombat]

It could be that the fan is introducing enough noise, or enough power drain, to disrupt the motherboard. I've seen it before on other motherboard/PS combinations, but usually running the CPU fan, but not case fan, off the MB was okay. Taking the case fan off of the MB header allowed me to overclock further (might have been on my 6167).

[Jon P. Inghram]

I've got a 60mm Delta finger slicer 6800 rpm fan on my PAL6035 that's got a third lead that doesn't appear to be for speed sensing, or at least not in a format that can be used by the motherboard header. And yes, I'm using an 3 pin -> Molex+RPM sense adaptor... it'd probably melt the motherboard down if I tried to use it directly off the header.

[Gurm]

Yeah I'm beginning to suspect (after reading some resources on the InterWeb) that ALL the motherboard headers tend to get their power from a single somewhat under-watted line.

- Gurm

[Wulfman]

btw, does the msi 745 use the temp-diode of the cpu to determine the temperature?

mfg
wulfman