Mobo: 945GCMX-S2 Gigabyte
CPU: Intel(R) Pentium(R) Dual CPU E2180 @ 2.00GHZ (2CPu's)
PSU: G-Force Switching Power Supply MODEL: ATX-500W +12V 20A
CPU fan in not spinning, it spins on boot but stops spinning after a few seconds or a minute

How do I know if the problem is the MOBO or the CPU fan?You could take a multimeter and test the motherboard fan connector:

Or you can just plug it into the SYS_FAN connector.
Is your CPU fan set on PWM control? In such a way that the temperatures at boot are low enough to stop it from running?- So I spin the MULTI meter to 12v?
-what is SYS_FAN connector?
-"Is your CPU fan set on PWM control? In such a way that the temperatures at boot are low enough to stop it from running?" I have no ideaYeah you just unplug the fan, boot the computer with the CPU fan CONNECTED to the motherboard at a connector labeled "SYS_FAN"

and then probe the CPU_FAN connector with the multimeter.
In your BIOS there might be a "Smart Fan" or "Fan Control" setting-if there is, set it to "Full Speed" or 100%

CPU fan set smart fan I Disabled it didn't spin
Enabled - Auto (no spin)
Enabled - PWM (no spin)
Enabled - Voltage (no spin)

My CPU fan was always connected to the motherboard

How do I probe the CPU_Fan connecter with the multimeter?
Where do I connect it?The CPU Fan has 4 pins, sys fan has 3 pins which 3 do I plug in?

How do I use the multimeter when there are 4 pins for the CPU Fan
Before we test with the multimeter,
Connect your CPU fan to the SYS_FAN like this:

Then power up your PC

Touch the Red Probe to the 12V pin on the motherboard, and the Black Probe to the GND pin on the motherboard's CPU_FAN connector.


So I set it to DCV 50? or ACV 50?DC. DC 12V. Its 12V, not 5VThere is ACV 10 50 250 1000 (it's in red) (written on the left) and the red wire is plugged on the right side of the multimeter
DCV 10 50 250 1000 (written on the right) (it's in white) and the black wire is plugged on the left side of the multimeter what next?Can I keep my CPU fan on SYS_FAN it's REALLLY REALLY SPINNING GOOODYes SYS_FAN always has full power coming out of the pins because on lower-end motherboards like yours there is no PWM cycle for the connector. You can leave it there without any issues-I do that with my computers too. I once had issues with plugging a 3-pin CPU fan into a 4-Pin connector-workaround was to plug it into SYS_FAN
YES IT WILL SPIN RRREEEALLLY FAST AND GOOD. Oh and I'm Pro Your Nab Live With it. Yes. I will Pro your Nab. (WHATEVER that means)