Dead comp?

[The_Other_One]

OK, I have this great mobo with a PIII 733 I'd been using for video editing for a while now. Nothing spectacular, but it did the job and kept my main comp free. Anyway, after making my new comp, I stuck the old 600MHz processor back in it and put it in storage(in my closet) Recently I pull it out to mess with it, and I get nothing. No beeps, no post, no video. I've tried different RAM, reseated and removed all I could, checked for shorts...nothing. I have not tried the 733MHz processor in it before, but I wouldn't think anything would be wrong with this 600MHz as it's been sitting in my closet too. I'm a bit afraid to try the processor as it could fry it(never know what's wrong) so does anyone have any suggestions? The 733 is back in it's original comp and it's working nicely...

 

[Scrat]

Measure the back-up battery... is it dead? if so try replacing it.

Using a DMM check the power rails while the systemis pluged in and turnned on... negative probe goes on PS case, then put the positive probe on the legs of any of the ICs on the MB and check for a voltage(cant remember which exact leg but it should be, but is one of the end ones)