Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

I bought a new dual-core Pentium 4 CPU (E5400) for my PowerEdge 850 (800Mhz FSB), and it's not even going through the POST. What am I missing? I updated the BIOS to the latest version (A04), and no luck.
share|improve this question
The E5400 is not considered a Pentium D… – Moab Aug 2 '10 at 15:20
My understanding is the core2 processors requires a special voltage regulatior on the motherboard, since Pentium D processors did not need this it will not be present on the motherboard, so no you cannot update to any core2 processor, you are stuck with Pentium Dual cores. I bios update will not solve it either, its a hardware issue. – Moab Dec 6 '10 at 17:18

The Pentium you bought is one of the new(ish) ones derived from the Core 2 line.

Just because it physically fits in the machine does not mean it is compatible. Sometimes you can get lucky and other times like now - unfortunately you are not lucky!

If it isn't working with the latest BIOS update, it means that it is not compatible - you can live in hope that they release an update in the future, but it is unlikely to find a machine/chipset that is compatible both with Pentium 4s and Core 2 era of CPUs

share|improve this answer

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.