Cpu fan not working on asus mobo,working fine on other mobos tried cpu fan connector, power connector and chassis connector with 4 different fans...

First remove the power plug from the smps and press the power switch few time and wait for few minutes the re plug the power connector to the smps and switch on the computer if you still dont have power then you will have to check whether the smps work to test that its not enough to test the voltage in the 21/24 pin you will have to short the green wire and the black wire and see whether the smps fan is working if the fan is not working then the problem is with smps

"i can find my dmm?" did you mean CAN'T?
"its clearly off", what is off?
the fans are 3 pins,2 are power, one is RPM tachometer.
"it all works fine", so you can boot and run any OS, ?

"the voltage reads +12vdc", where, at fan or PSU?
the fans run off 12vdc, they are DC motors (from outside fan)
if the fan runs slow at 12vdc the the fan is bad or is a low RPM
fan, as some are, bigger fans run slow, for less noise.!

first is the CPU fan it must run full speed, if not the CPU will overheat in seconds and ALL CPU shut them selves (by there selves) this way. so CPU fan is first. what does it do... there....?

then BIOS screens. GOT BIOS UP? and running? with, ESC key pressed>.
let me guess your symptoms
1: PC dead. will not boot.
2: BIOS dead.
3: all fans DEAD,.
4: power switch works and all PSU voltages read right, (seems not)/?
5: if the PSU power wire reads right(DMM), matching the side sticker voltages, and the CPU is dead, the MOBO is dead, or CPU is toasted.


here is a modern PSU, sticker.
see 5 to 10 power lines, see them. all must read correctly
if a fan is dead, then its dead if 12vdc is present on the fan power pins.

HI,
Clear CMOS or remove CMOS battery, Press the on off switch for 30 seconds.
Now go to BIOS setup,and set bios fail save default,and press F10>enter.If the problem same change the RAM if you have a spare.
http://www.computerhope.com/help/phoenix.htm

Hope it helps.

Most motherboards now have a 24-pin power supply connector. If you haven't already found a diagram showing the pinouts of the 20- and 24-pin power plugs, here's one borrowed from a handy site:



The two plugs are essentially the same, but the 24-pin version duplicates some voltages on the extra pins. The extra pins in the larger connector were meant to provide extra current paths for voltages that see heavy loads from newer processors and motherboard circuitry. Depending on how a motherboard is designed, it might work with a 20-pin plug connected (leaving pins 11, 12, 23 and 24 empty). But typically if the board has a 24-pin connector it needs the 24-pin power supply plug.

Most power supplies have a 20-pin plug with a separate 4-pin section that fastens to it for connection to a 24-pin mobo connector. It typically has one side designed to slide onto the end of the 20-pin plug, essentially turning it into the 24-pin version. This added plug does not have a retaining clamp on its side, so you can tell it from the the 4-pin CPU power plug. The wire colors are also different. For reference, here is the processor power plug, from the same website:


New motherboard specs call for the separate processor power connector for the same reason the extra pins were added to the power supply connector: to handle the high currents needed by increasingly faster CPUs.

When the motherboard has these connectors, you need to use them all to get everything working. Hope this helps. Thanks to smspowersupply.com for the diagrams, and thank you for using Fixya.

The spray on the MB should not be a problem - unless it was plugged in when you did it. Yes, you should be able to put in a new Dell motherboard. As long as the processor is of the same class, the Dell license should work fine. However, you may need to download new drivers for the machine to run.

If you really want to check the power supply, I would suggest you buy a tester. They are fairly cheap: $10-50. You want to be sure that your board is getting the right power at the right places. 12 V to the fan is fine. However, 3.3 v or 1.5 v?

It sounds like you have done a fairly good test of the motherboard. I've definitely seen bad Dell motherboards with the light on with/without a bad power supply.

If you have another case (an ATX), I would buy an Asus or other motherboard and put your equipment in it. The cost of a Dell motherboard is excessive. Of course, you will have license problems with XP.

the problem is that the mother board you are now using has a 4th wire that sences cpu temp this allow the heat sink fan to change speed to get this to work correctly you will need to replace the fan with a 4 wire style. what is happening is your not getting a temp siginal back to motherboard so the fan controller think it hot and send full power to fan alll the time the stock fan in hp systems is not very good any way .Get a good heat sink and fan to fit your new board ebay has them very cheap 5.00 to 20.00 this will all so increase you system temp and all get the proper cooling when you really need it.

This sounds like an overheat problem, is your cooling fan working properly, also the processor you are using is a powerful one, so needs a cooling fan much more powerful than the lesser powered athlon 64 processors.

try taking out a gig of ram and then start computer.

click here

this could help you

Don't mean to butt in here but I'll bet the 4 pin_ATX 12v connector is not connected to the board. That 4 pin_ATX 12v connector give's the CPU it's power. Without is the system will not boot. Some boards will give off that weird sound you are hearing.