knackered motherboard has no CPU fan power, is this fixable?

[bennyt]

Hi,

I acquired a knackered ASUS A7A266 mb. Although there is absolutely no visible sign of damage, the CPU/chasis fans get no power from the board - and it will not boot with with even the barest configuration (128mb PC2100, TNT2 GFX, Duron 1GHz, power supply). Unfortunately I do not know what caused the board to stop worknig in the first place.

i)Any guru know what part of the mb controls the power, i.e. where I should be looking for a problem?
ii)Is there any realistic chance of fixing this or could it be one of a hundred problems and I am just wasting my time?

I would like to know it is COMPLETELY broken before I chuck it out http://www.PCGuide.com/ubb/smile.gif
Many thanks,
Ben

ps I have taken care of the CPU cooling through other fans for the time being http://www.PCGuide.com/ubb/smile.gif

[rond36]

The Asus A7A266 like most newer motherboards with a PC health utility in the BIOS will not boot if it doesn't find a CPU fan spinning at the proper RPM plugged into the CPU fan header. This motherboard is trash unless you can find someone that can fix it! This problem is caused by putting too large and or fast of a fan on the CPU fan header. A large fast fan draws too much power and burns out the fan header.

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[bennyt]

Thanks rond,

so do you have any idea how a blown fan header can be repaired - or where it is located on the board? There is no evidence of a major burnout on the board.

Long shot I know http://www.PCGuide.com/ubb/smile.gif

Appreciated

[JonathanB]

Try to disable the fan monitor in the Setup (if possible). I have an ASUS p3v4x and I prefer to get my CPU fan power from the extra socket of the Power Supply itself (not from the power of the mobo). But I have to replace the sockets. This way the mobo is not overloaded. But the Fan Monitor in Setup should be disabled.

[bennyt]

I think I should be a bit clearer... sorry.
Please read won't boot as won't POST - can't even get video.
There is power to the graphics card cooler and the processor/chipset warms up but that's about it.

Thanks for the suggestions though.
Ben

[ski]

Consider replacing the MB. Getting it repaired can cost as much as buying a new one.
Besides, the fan header may not be the only problem with it.

[Rick]

One other thing you may want to try Before you drop that MB in the recycle bin.
The Bios is looking for the Tach lead out put.

You can buy a fan with a 3 wire split connector .
One lead goes to the Tach (3 pin header on MB) the other goes to the 4 pin connector from the system power supply.

When connected it will spin the fans at boot off the power supply relieving the MB of the burden
And still allow for the PC health / system / Fan monitor to operate correctly.

Here s a link to one http://www.kdcomputers.com/eui/prime/profile/411/26/component.htm
NOTE. The above is a SCREAMER .. 46db,, LOUD..

If you look at the connectors you will see it isn’t that hard to make one of these using an existing fan with 3 pin MB header tach/power leads .
Simply cut the red and black leads from the Header(3 pin) and attach them to the correct posts of a 4 pin connector for use with the power supply connector ( Note Yellow and Black On power supply connector are 12 Volt)

[ranchdog]

Ben

Fan "header" is to say the 12V fan circuit on the board. It
may be possible to save this board by using an extra fan that
does have an RPM sensing wire. Fan wires are Red (12V) Black
(Grnd) and the odd color is the RPM wire (White, Yellow).

Cut loose the Red and Black wires and plug in the connector
with just the RPM wire to the CPU Fan plug. Take the Red and
Black wires somewhere for a splice. Maybe to case fan wiring.

This could be done with the original Heatsink Fan if you need. I
have botched a couple fan headers with heavy duty CPU fans and
had to go to this method rather than retire the Mboard.

The trick is to have a fan of some sort spinning and its RPM
sensing wire plugged into the CPU Fan connection.


Luck.

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[bennyt]

I'm sorry to say that after trying that out I still have had no success http://www.PCGuide.com/ubb/frown.gif
It is quite possible that the problem goes deeper than just a knackered fan circuit.

I think the board will be seeing the inside of a garbage bag pretty soon...
Thanks a lot for the suggestions though - it's all good for future reference http://www.PCGuide.com/ubb/smile.gif

Ben

[Rick]

Sorry to hear it didn’t work.
It’s a lot cheaper to replace fans that the M/B.

[mjc]

Before you send it off to that final resting place...after you hooked up the new fan did you clear the CMOS using the jumper?

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[bennyt]

Strange as it sounds the board doesn't actually appear to have one. However, I pulled the small round battery out (power for the bios, right?). Seems a waste I know but I think that has exhausted it.

Regs,
Ben

[Paleo Pete]

OK, let's back up and check a couple of things that haven't been looked at so far.

Pull the motherboard out of the case and try it on a tabletop or peice of cardboard. See if it at least gets video at all. Use known good video and memory, known good CPU would help too. You need only motherboard, CPU, memory, video card and keyboard.

Swap out existing memory and video card to see if either might be bad.

You didn't say if this computer had ever run so I'm guessing...

Are you using a known good power supply and are the connections correct?

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[bennyt]

I acquired it for nothing and no I have never seen it working. I do not know what condition it was in before the previous owner stopped using it.

None of the onboard fan headers provide any power.

The board has not ever been in a case and I have been testing with a minimal configuration (RAM, gfx, processor, power). All known working components.

As I said before, graphics is not initialising. Apart from that there are no visible problems. In all likelihood the board is dead but I wasn't going to quit without a fight.

Ben

[Rick]

Check the manual for the MB.
The Clear Cmos is not a jumper on that board.
It has two points on the board you need to short / jump.

I use a very small screw driver to short the points

[ranchdog]

Heck Ben...

Don't give up yet. The Fat Lady isn't singing.

Ask around and find someone running an Asus board,
slip your BIOS chip onto another working board, disable
the CPU Fan Safety in CMOS and you're home free.


Luck.

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....How long is a minute... depends on which side of the Bathroom door you're on. ......
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[bennyt]

You reckon that'll work?
Well I won't chuck the board out and if the opportunity arises I shall give it a try.

But I've actually had a fan with the tachometer connection hooked up and it still wouldn't budge.

One last thing (... http://www.PCGuide.com/ubb/biggrin.gif):- I have a Duron 1GHz on the board. But, the FAQ for the board says that _Morgan_ core chips are only supported by Bios v1.10 I have a feeling that my Duron (it's new btw) may have a Morgan core..

I have no idea what Bios version is present but I _doubt_ it is 1.10. Is this going to work?

Comments..?
(thanks guys http://www.PCGuide.com/ubb/smile.gif)

[Rick]

In that case you may want to find someone with an old chip and drop it in.
Then flash the Bios and replace with your chip..

Also double check the jumpers for Jumpered or jumper free settings