PC will not power up. No fans, lights, anything.

Admittedly, this could still be your power supply (PSU). Perhaps you did attach the 24 pin motherboard (MB) connection to a tester, but since the post does not specifically mention this I presume you may not have. Forgive me if that was done.

Assuming the test was only jumping the 24 pin connection verifying that fans kicked on; my guess would be that the PSU still functions. However, it may no longer be producing enough juice to power the PC.

If you have not done so already, I recommend testing the power supply against a tester to verify that you are getting enough voltage to power the motherboard.

Do any lights come on at the case? eg at the front or on the port where the network cable is plugged in.
Does the psu fan spin when turned on?
If you can open the case, there is usually a green(?) led on the motherboard that lights up when powered on.
If nothing is happening, it could be your power supply. Try swapping it with a spare one (check that it is a standard pin layout.
Look at ebay, local pc store etc for a cheap atx psu tester to see it the power supply is ok. Or google how to jump start a pc power supply with a paperclip and/or test with a cheap multimeter - usually with the green and black wire from memory. (careful playing with electricity though and read up on how to not short out your computer and damage something else).
Otherwise, the motherboard itself may be dead.

When powering on the PC and you get no beeps, but you are getting power to the fans and hard drives, this may indicate either a bad power supply or bad memory. You can take the machine into a pc repair shop and have them test the memory and PSU for you.

Step 1 - Check that all your cables are connected properly.
Step 2 - Check your power supply with a PSU tester.


You can get a PSU tester here:
http://www.newegg.com/Product/ProductList.aspx?Submit=ENE&N=-1&IsNodeId=1&Description=psu%20tester&bop=And&Order=RATING&PageSize=100

Even though the fans are running it doesn't mean the power supply is ok. Buy a PSU tester or bring it to a computer shop to have the power supply tested.

I work on computers everyday and it sounds like the power supply. Do you have access to a tester? If not just take out the power supply and run it up to a shop, I'm sure they'd be glad to test it free of charge. Hope this helps. Lets hope it's the PSU, it's the cheapest to replace!

Is the fan that cools the CPU running? This sounds like the CPU is overheating. You can download and run a temperature monitor to test this.

It seems that the power supply unit has gone. If you power it on and nothing happens then obviously the psu has gone. The heat that you felt was the psu overheating because of no fan and hence no ventilation. The noise was of the faulty psu fan that got stuck or did not work and the psu got overheated and got burnt eventually. Please replace it with a new one as a repaired psu may work but you cant rely on it.

It is definitely the PSU that's not working properly,because defective motherboard should still receive the 12V. you can use a desktop standard power supply to check if the server runs fine, even a cheap one is ok for a test run. they sell also cheap (about 15-20$) PSU tester, definitely worth when working with servers and WS.
the Power supply fan might have a dedicated rail coming from the thermal sensor(thermistor.)this is why it can run even with bad 12V rail.

A great way to test a PSU is to use a PSU Tester. The device allows you to see if all the circuits are getting power and it only requires you to plug it in to power. This allows the ability to test it safe and reliably without accidentally damaging hardware. Below is a link to a tester.

PSU Tester