Dell Optiplex SX260 Computer Won't Boot Up

Hi,

UPDATE:

Sure enough, I have found several electrolytic capacitors (tested out of
circuit) which include every one of the eight 2200UF 6.3V (next to each other
and connected in parallel). As for the brand on these bad (2200/6.3) caps, I
can see what looks like "2DIVDK" and there is a "M" in a circle on another
part of the cap.

There were no bulges in any cap, but a loss of capacitance such as
measured via a digital cap tester showing around 1500uf for these 2200/6.3
caps. Often an increase in ESR can cause a lower cap reading on this tester.
My ESR meter is not useful on large capacity caps.

I will have to order replacements, but since I have other good working
computers, I am in no hurry.

Thanks again to everyone for your replies, John