Pc won't boot with other cpu's

[Urban101]

Hi, I have recently attempted to install a core 2 quad q8300 into my HP 500B MT, and was met with 1 short beep and one long beep. I was then told that my cpu was not compatible, and after purchasing a compatible cpu (core 2 duo e8500) I still receive the same error. Multiple attempts at searching online show that it may be a memory issue, however I have tried reseating the Ram and testing each slot to no avail. What's confusing is, the pc will only run with the old cpu in (celeron E3300) 

[Paul_Tikkanen]

Hi:

Did you update the BIOS to the latest version?

HP 500B Microtower PC Software and Driver Downloads | HP® Customer Support

The latest BIOS is 6.05.

Since the PC works fine with the original processor installed, I would rule out the memory being a problem.

[Prométhée]

hi

indeed according to this document

 Illustrated Parts & Service Map: HP 500B MT Business PC

1 short, 1 long Bad memory or memory configuration error
Check that the memory modules
have been installed correctly and
that proper modules are used.

https://support.hp.com/us-en/product/hp-500b-microtower-pc/4191793/manuals

if you have several memory modules try one after the other, maybe

[Urban101]

Hi, reinstalled the stock cpu and  I have checked the bios version using the command prompt and it states that the bios version is 6.05, and adding to the ram suggestion, Windows has detected all 4gb of ram present.