DELL OPTIPLEX 980 won't boot

[wjwise001]

HELLO Guys....I have a dell optiplex 980 desktop which was working yesterday but after powering it off.....it can't boot today, it just turn on and off over again with 1-3 error code....I've tried replacing CMOS and PSU but to no avail PLEASE help me out cos am freaking out.

 

[william p]

http://www.dell.com/support/home/us/en/04/product-support/product/optiplex-980/manuals
Here are the 3 manuals for the 3 Opti 980s. By 1-3 code do you mean beep codes, or the #1 and #3 diagnostic LEDs that Dells come with in the front panel?

 

[wjwise001]

So....isn't it an internal hardware problem. Cos I've tried using the RAM one by one but can't detect the fault.
I just want to know what's the main cause of the system not booting so please help