Here's the problem: I replaced the mobo (P4VMM2) and RAM in my computer. (Reason for replacement: POST gave a beep code indicating the onboard video was shot) I do not have the Hard drive, CD drive, floppy drive attached to the system. Only the Power supply, RAM, CPU are functioning). I started the computer once, and got a message on the POST screen that said the CPU had changed, or the frequency was incorrect. I wrote on this forum, and got a suggestion. I powered on my PC, and the fans were spinning, but it did not boot! I waited 5 minutes, and powered on the computer - it started up, giving a message that said "CMOS Checksum error - defaults loaded) I was able to into the BIOS screen, and didn't change anything. I tried to continue booting, expecting to see a "missing OS" error, as there was no hard drive. But , the monitor turned off, even though the fans were spinning and it still had power. It stayed like that until I turned it off with the power button. I tried to turn it on, and , you guessed it, fans spin, power lights are on, but nothing. I just changed the mobo AND memory. What could the problem be? The old mobo was a P4VMM2, and it had the Via 8233 chipset. The new mobo is a P4VMM@ v8.1, running the Via 8235 chipset. I talked to the tech dept at the place I bought it, and they said the boards were comopatible. SO I don't know what's going on. Any help is welcomed

"Reason for replacement: POST gave a beep code indicating the onboard video was shot" I don't know if it was actually "shot" or not, but you could have saved yourself some money & hassle by just installing a videocard & disabling the onboard... "CMOS Checksum error - defaults loaded" Defaults settings are NEVER the best settings...they are a starting point or a fallback point only. Every BIOS should be "customized" to the hardware installed on the system Asus A7N8X-X 1800+ @ 8.5 x 200MHz 768MB PC3200 2.5-3-3-7 Asus A9550GE/TD 128MB WinME/WinXP Pro

I think you have a mother board grounding out on the case.Try Rubber washers for standoffs.I had the same problem.I bought rubber washers,super glued them to the screw holesw on my motherboard and ended my problem.I could be wrong but,my problems were same as yours.