On Thursday, February 14, 2013 8:29:13 AM UTC-7, wrote:

I have a Dell Optiplex SX260 small desktop type computer that won't
boot up. When I press the power button, there is no display on monitor, no
HDD spin up noise. The only "life" I see/hear is the power light comes on and
the fans run. I tried a bootable CD, but the CD drive doesn't "run".

I checked all the on board fuses (all good), solder joints, and power
supply output voltages with a load. The CMOS (RTC) battery is good.
I even removed and reinstalled the CPU.

Many Dell Pentium 4 motherboards contain bad Nichicon brand capacitors because Nichicon goofed up the production of models HM(M) and HN(M) from about 2002-2004. The date codes are in the form LYYMM, where L is a letter, YY = last 2 digits of the year, and MM = week of the year. So H0324 means the year 2003, week #24. 4-5 of those capacitors are 1500uF, 6.3V, 10mm diameter and located around the DIMM sockets and AGP socket. Behind the CPU are about ten 1800uF, 6.3V, 8mm caps and another 3-4 1800uF, 16V, 10mm caps on the other side of the MOSFET heatsink. Those may be Rubycon brand (big "K" stamped in the tops) model MBZ or MCZ instead of Nichicon (big "+" stamped into tops). The Rubycons were never defective, but TheCapKing.com says the Pentium4 was so power hungry that even those caps can go bad in 5 years. Most caps in motherboards can't be tested with an ESR meter except by unsoldering them because so many are in parallel.

Some people replace conventional wet electrolytic caps with dry solid polymer caps, which are more durable in heat. Here's some information about doing that:

http://www.badcaps.net/forum/showthr...ghlight=gx-270

BadCaps.net not only has a great deal of information but also sells high quality caps.

Be careful about counterfeit caps. DealExtreme has sold them, some being pretty obvious fakes (Teapo brans substituted from Sanyo or Nichicon), and apparently only one Ebay dealer sells only genuine caps:

http://stores.ebay.com/PC-MotherBoard-Capacitors-Store