Freak PC Problems.

[Cloud 8]

Right, First things first; Hi Everyone! Long time ghost, first time post ^^

The issue is about 2 PCs, but theyre related, so bear with me.
OEM PC:
Q6600 G0, 2GB DDR2 667 Generic RAM, 300W Bestec PSU, G33T-AM Motherboard.

Custom PC (The plugged in one):
Q6600 G0, 4GB DDR2 800 Crucial Ballistix RAM, 600W Modular Jeantech PSU, ASUS P5WDG2 WS PRO Motherboard.

About a week ago I had a power cut in my home. One of the PCs was plugged in, the other was not. The PC that was plugged in has since refused to turn on, but Motherboard is recieving power and all components are intact. I managed to get it to post once, by resetting the CMOS and killing power so that it turned on by itself when it got plugged in again. This only worked the once, havent been able to repeat that.
I have tested the parts in other rigs, and all of them are fine. Eventually though, I gave up and switched the motherboard and PSU with the one from the Unplugged rig; an OEM Philips machine. Now THIS one has the same problem. So, I removed all the hardware from both sets and have stripped them so they are them out as follows:

The PC that was plugged in:
CPU, Motherboard, Processor, Fan, PSU.

PC that wasnt plugged in:
CPU, Motherboard, Processor, Fan, PSU, RAM. < All of these are the OEM machine parts.

They are layed out on foam, outside of the case.

Both of them are not turning on, both show motherboard is recieving power but will not turn on. Its like I press the switch and it recognises nothing. I have tried 3 sets of switches (the one from the OEM case, the one from my NZXT Case, and a Case Open switch) and shorting it with a screwdriver. All to no avail

Ive tried replacing all the parts interchangably, but without success. My prime suspects are the motherboards, but then why did the ASUS board turn on after the CMOS reset?
The Philips machine also turned on once automatically in the same way, but the CPU fan did not spin. I tried removing the CPU fan in case of a short, but then when I tried to replicate the automatic power on, just like the ASUS board, it did nothing.

Any Ideas?

Thanks in advance -
Cloud.

 

[tiraides]

If you can, please give us the specific model numbers to the power supplies in both machines (as well as, if you can find it, the manufacturer's name of the generic PSU).

In addition to trying some of the steps listed in the troubleshooting sticky, you may also want to buy a new CMOS battery (which is a CR2032 watch battery that can be found at many stores) and try resetting your CMOS (with the new battery in place) again.

Other than the above, I don't really know what else I could tell you.

 

[Cloud 8]

Thanks for the advice, I'll pick up a couple batteries and try them out, as well as reading the sticky you mentioned.
The Jeantech model no. is JN120F-600P12V2, and the generic one is a Bestec ATX-300-12EB3.
Also, apologies for the mistatement on PSU watts, I thought it was a 450W, but its a 300. My bad.

 

[Cloud 8]

Thanks a million, the new CMOS battery revived the ASUS board
Gonna pick up a 2nd one and try it in the philips in the morning.
Thanks again!

 

[tiraides]

That's good to hear that the battery swap was all that you needed (for the Asus board).

For the future, I recommend two things for each system: a surge protector/UPS and a new power supply. I believe that the power supplies you currently have took most of the brunt of the damage, so they may not last much longer. (Plus, they're both generic brands that we wouldn't recommend normally). Two power supplies to consider in the long run are the Antec Earthwatts EA380 and the Corsair CX400. The surge protector would protect you in case an incident like this happens again, but I recommend an UPS instead, as the battery backup that it includes would also give you enough time to properly shut down your system.