Failed power supply?

[jruggles]

I suspect that the power supply on my computer has failed, I get no indication of power in the system. I am replacing it with another power supply that I have. The motherboard is a PC Chips M789CG. All of the connectors, from the power supply, fit but the one going to the CPU fan (SYSTEM_FAN1). The connector on the power supply is four prong (2 12v + 2 ground) the motherbord has three prongs on it, two of them are ground, I need to know hot prong voltage is, can't seem to find that info,

[Whyzman]

The 3 pin motherboard header has Power, Ground, and an RPM sensor wire. The RPM sensor wire is used by most new motherboards to be able to power up. In the event that the CPU fan is not turning, they will shut down immediately to avoid overheating the CPU...

It appears you may have the standard 4 pin Molex connector from the PSU...

I actually use a molex adapter to avoid connecting the 12V CPU fan directly to the motherboard. The adapter I use does have the RPM sensing lead which is necessary...so a single wire connects to the header...

I suspect that you may be able to power the CPU fan directly from the motherboard header (be sure it is the CPU FAN header or the system will not power up). Using the PSU directly for the CPU fan should not be necessary...

Does the CPU fan connector have the small 3 pin that fits the motherboard header?

Also, welcome tohttp://www.pcguide.com/ubb/pcgubb.gif Forums!

[jruggles]

The fan plugs into the motherboard, the connector from the power supply plugs into the motherboard also. Per the user guide the connector in question runs the fan. Thanks for the info. do you know where I might get an adapter plug?

[Whyzman]

Here's what they look like: http://www.xpcgear.com/3to4pinycabw.html

I cannot vouch for the supplier... Usually, most computer stores these days carry them due to the number of folks desiring to power their fans directly from the PSU

You should be able to test the motherboard, if that's ultimately what you want to do without the System Fan connected...just for power up/troubleshooting purposes...

As mentioned above, the CPU fan is the critical connection for powering up...

Sorry, I didn't see that you were referring to the System Fan initially...

[Whyzman]

Oops...

I usually keep a few of these on hand...they're cheap and whenever I am building I also remove the CPU fan from the motherboard header using the adapter...