Cpu voltage

You're ok; your software isn't calibrated properly or may not work with your motherboard. List your specs for more help.

Hi and welcome to Tom's forum.

Like o1die says, please list the specs of your rig and specially the brand and model of your PSU. IMO that 15.5 on +12V is a little high.

My motherboard is an Asus P4P8X My cpu is an Intel pentium 4 2.40 GH

Check your voltage readings in the board bios next time you reboot; use the "del" key and look for a hardware monitor section.

Is your rig a build rig? Looks like a HP or DELL rig, if that is the case the PSU isn't the best one.

I don't think the P4P8X has a hardware monitor for system voltages, only fan speeds. I had one back in the day, and I only remember seeing fan speeds in the bios setup, not voltage monitoring. You can, however, set CPU, RAM, and AGP vRef voltages, but not monitor them.

Thanks...

will do

I know this doesn't answer your problem, but if you have a microcenter nearby, you can build a new Phenom II x2 build for $200. I just built 2 and one unlocked to an x4 and overclocked nicely. Since you're running a P4, I thought I'd let you know how cheap some of your options are in regards to replacing an old rig.