installed second processor in hp xw9300 now windows won't boot

I have dual opteron 285's now both are exactly the same, I had windows 7 ultimate 64 installed and working with just one cpu, now after installing the other processor windows 7 constantly resets back to the post screen (where you would hit f10 to boot f12 for bios etc). checking the bios shows that both cpus are working, both have 4x512mb dimms making a total of 4gb of system memory. im getting results saying that windows 7 only supports 1 processor with 258 cores or 2 processors total 258 cores, neither is possible so im not sure where to go from there, trying to reinstall windows with both cpus in hangs at the loading part after windows loads files, installing server 2012 also hangs and resets back to post. what is going on?

In dual CPU systems both CPUs must be a very close match. Being the same model number is not good enough. All significant specifications must match and they must be designed to operate as a pair. This is often a problem when the CPUs are not purchased at the same time. In some cases the CPUs must be purchased as a matched pair.

The BIOS can only detect that the CPUs are present. It cannot know they are capable of working together.

can you elaborate a little more? the model on the heat shroud is also the exact same for both, and they where purchased at the same time in 2005, it originally had a single opteron 252 which wasn't upgraded until today, also both where purchased from hp's website. essentially in 2005-06 the machine had the intention of being upgraded and never was, it was taken out of the closet and only works with one processor, cpu mounts work along with changing which cpus go in which mount so hardware isn't at fault.

Sorry, this is not my area of expertise. I was simple pointing out things that were not mentioned in the original post.

thanks, i've done this with my bios physical reset button, ive also pulled the battery, as for a jumper ill have to look for one since im not sure its there

after messing with it more i decided ro load windows xp and to my surprise it actually went further in the installation process going as far as to fully install the OS and boot into it however i get a blank blue screen where you would normally see your profiles and waiting about a minute the blue screen would show splotches of white, i think now this may be a ram problem with the second processor since the single cpu configuration works fine with all of it's dimms filled

ziggieice said:

after messing with it more i decided ro load windows xp and to my surprise it actually went further in the installation process going as far as to fully install the OS and boot into it however i get a blank blue screen where you would normally see your profiles and waiting about a minute the blue screen would show splotches of white, i think now this may be a ram problem with the second processor since the single cpu configuration works fine with all of it's dimms filled

after reseting the bios again im getting error 201- memory test failed, telling me to isolate ram, however rebooting gets rid of this message,

problem solved, miss-matched ram brand manufactures on cpu1 caused it to not boot, so i took the 2x512 ram modules from cpu0 and put them into cpu1 dimm slots(these are hp branded) and it boots and works, this leads me to believe hp has their server workstations on brand lock down so only hp certified ram and hp branded ram are the only modules that will work