Slow Computer with High CPU Usage

[Akroy]

I just moved my motherboard, RAM, CPU, and graphics card to a new case with a new power supply. There is an old hard drive in, but it has been freshly formatted and had Windows XP Home installed. It however is extremely slow even though it has pretty decent parts. Booting up takes forever even before the OS comes up and then the OS takes forever to come up and is ridiculously slow. The CPU usage is 100% when first boot up and then decreases to 70%. Generally it runs at 0% or 1% when it's just sitting there at the desktop.

Since it is slow before the OS comes up and goes through POST and BIOS slowly even when no drive is plugged in, I don't think the hard drive is the problem. I don't think there could be a virus in the BIOS or anything since these parts all worked in the other case with the other hard drive. The RAM doesn't seem to be the problem since I tried other RAM which I know is good and it was still slow. I thought that maybe the CPU wasn't getting enough power, so I tried a different power supply and nothing changed. I reset the CMOS as well.

Here are the parts that I have in right now. I'm going to be using some other stuff as well, but for the purpose of troubleshooting, I've removed everything else.

Motherboard
ABN-SLI Premium

CPU
2.21 GHz AMD Athlon 64 X2 Dual Core Processor 4400+

RAM
2x512 Mushkin Advanced Blue Series
2x1024 Mushkin Advanced Blue Series

Graphics Card
EVGA GeForce 7800 GT

Hard Drive
Western Digital 160 GB

Power Supply
PC Power and Cooling 500 W

 

[patonb]

Try only 1, 1 gig stick of ram.

 

[Akroy]

I've tried that. I've tried each of my three kinds of ram individually. Everything is compatible and drivers are installed, so I'm not sure what the problem could be. If my CPU was going bad would this be what would happen?

 

[carnageX]

Try doing a chkdsk on the drive, just to make sure it's not actually the drive.

 

[Akroy]

I ran chkdisk from the command prompt and it found nothing. Then I tried booting from my drive in my other computer (which incidently is SATA while the one in slow computer is IDE) and it ran perfectly normal. I can't figure out why the computer is slow before the OS even comes up with the IDE drive though. Since chkdisk didn't find any problems with the drive, I decided that maybe something is wrong with the OS, so I'm reinstalling Windows. It's in the middle of that now, but it's going very slow, so I'm not optimistic about that.

I tried again with that same hard drive that worked earlier and it was very slow. Then I tried with a different SATA hard drive. So I think it's safe to say that the hard drive is not the problem as I've tried quite a few different ones, some SATA and some IDE with various different cables.