Gigabyte ga-ep45-ud3p - cpu fan

[YankeeRedneck]

Is it normal for the cpu fan/heatsink to not spin during bootup?
I am doing a new build and the fan does not spin.
Gigabyte MB / Cooler Master TX2.
I have not loaded any software and only had it powered up for
about 5 minutes or so. I put my finger on cpu cooling pipes
and they were NOT warm whatsoever. The cooler master has
3 socket plug and CPU_FAN is 4 pin. I put the plug in such
that 1 pin was correctly placed, leaving the 4th pin exposed.

Is it ok to attach the cable this way? Is it ok that the cpu did not
get warm (no load?) and fan did not spin? thanks

[Svengali]

Re: Gigabyte ga-ep45-ud3p - cpu fan

If you check the pinouts for a 3-pin fan vs. a 4-pin fan, you should be ok to hook it up that way. It should spin though. Because it isn't, I suspect that the CPU header is not supplying 12v to pin 2. This could be because the control pin (4) is not connected. You could check this with a voltmeter to verify. I'm not sure that you'll ever get any voltage out of this connector without having the 4th pin connected. The 4 pin fans vary their speed using the control pin (this is called PWM). The output voltage is based on the CPU temperature that the motherboard senses. I think with a 3 pin fan connector, you would be better off connecting your CPU fan to another 3 pin header that is available, either PWR_FAN or SYS_FAN1. These will always supply 12v to pin 2 which is what you want. On my system it takes a little while for the CPU to heat up enough to start the fan, but I'm using a PWM fan on my CPU heatsink. Hope this helps.

P.S. - Nice Avatar!

[hawaiian_geek]

Re: Gigabyte ga-ep45-ud3p - cpu fan

It could be the fan on that CM hsf is dead. Plug it into another fan header on the mobo to see if it spins. It shouldn't matter if the fan is 3 or 4 pin. I use a CM Hyper 212 that only has a 3pin. Or the cpu fan header is dead. If that's the case I'd get a brand new UD3P from where ever you bought it from.

[profJim]

Re: Gigabyte ga-ep45-ud3p - cpu fan

Check out pages 59 - 60 in your mobo user's manual.
The PC Health Status panel deals with settings for fan modes and failure warnings.
I've disabled Cpu Smart Fan mode and control, and have my fans hooked up to fan controllers. It helps that my fans are quiet when running at 80% of their rated speeds.

[YankeeRedneck]

Re: Gigabyte ga-ep45-ud3p - cpu fan

I forgot to state that the fan moves for a "split second" when
I first hit the power button on the case. Then it stops.
The 2 case fans, along with video card fan work fine.

As far as making changes in the bios, that is a no go.
Cant even get it to post to get to bios screen, so I can't disable
anything in there.

Does the MB somehow sense that the cpu heatsink fan does not
work and thus prevents it from bootup?

Should I leave it powered up for a couple of hours to see if the fan comes on? Should the fan be on all the time even though the cpu is cool/cold to the touch?

[YankeeRedneck]

Re: Gigabyte ga-ep45-ud3p - cpu fan

OK. Hit me upside the head. I did not have the ATX_12V power cord plugged into MB.
I plugged the 24 pin power cord in last night and totally forgot about the ATX_12V connectors!! I guess this explains why SYS_FAN did not work, CPU did not get power, keyboard would not work, would not post, no signal to monitor.....................

[hawaiian_geek]

Re: Gigabyte ga-ep45-ud3p - cpu fan

OK. Hit me upside the head. I did not have the ATX_12V power cord plugged into MB.
I plugged the 24 pin power cord in last night and totally forgot about the ATX_12V connectors!! I guess this explains why SYS_FAN did not work, CPU did not get power, keyboard would not work, would not post, no signal to monitor.....................

At least you got it all figured out now.....Have fun with your build!

[profJim]

Re: Gigabyte ga-ep45-ud3p - cpu fan

OK. Hit me upside the head. I did not have the ATX_12V power cord plugged into MB.

OK, you asked for it....


A bit of useful trivia, the Sys_Fan2 (next to the purple sata slots) under-volts any fan connected to it by 50 -55%. All the other fan headers run attached fans at full speed. Some fans don't under-volt well and won't start if connected to the Sys_Fan2 header.

In another thread, a rookie posted that his system would only remain on for 5 - 30 seconds and then power down. His problem was the cpu HSF; two of the pushpins did not fully seat into the mobo. In days gone by, his cpu would have been toast. Luckily Intel did it right in their thermal design and his system shutdown prevented damage to his cpu.