Computer boot up

I've been having this problem ever since i built my pc. Here is a video showing
what happens.

View My Video

I don't know alot about bios configuration so any help is greatly appreciated!

I saw a message... no hard disk detected... then it looks like windows starts to boot.... tell us what your problem is.

Was that two monitors I saw? Are you trying to set up a multi display? Like anonymous1 mentioned, the curious points are the no hard disk message followed by Windows 7 attempting to start.

My suspect list is:

1. Failing PSU
2. Failing HDD
3. Failing HDD interface

Without knowing the specs of your system, suggesting places to start would just taking shots in the dark. For what it's worth, you can try our standard troubleshooting checklist. Just follow the link in my signature. If you want more directly related to your problem, you'll need to post your system specs and give details of the problem. We can see the video and assume the problem is the your system doesn't boot, but if you could provide the details, that would make helping you easier.

In the BIOS you can set HDD priorites, or disable boot devices altogether, but there isn't any setting that will cause the drives to randomly boot. The reason for my suspect list is that you're having difficulty getting past POST because the boot drive isn't being detected. While everything may be fine once Windows boots, the concern is that booting is intermittent.

You may want to test the PSU anyway. Just because the output (1000W) is clearly enough, there could be something wrong internally. Testing the PSU with a digital multimeter would be the most ideal way, but you can try reducing the load on the PSU by removing unecessary devices. Start the computer with just the basics:

1. CPU/HSF
2. RAM
3. Boot HDD/SSD (meaning the drive that Win7 is installed on)
4. 1 GPU

I am having the same problem with a different machine. It just says "no hard disks detected" one time and then boots to Windows. I've ignored it for a year, but now I'm (finally) upgrading to Windows 7 and I can't boot from the installation disc. I can't access BIOS. No, it's not my keyboard: I pause the screen and am given the option to go to the boot menu or BIOS, I select either one, and then it goes to the "no hard disks detected" screen and boots Windows.

I have searched these forums and others for hours and have not found a solution, which is interesting, because I've seen this issue a handful of times.

A790GXM-AD3
amd athlon ii x4 640
Hitachi 0F10381 Hard Drive - 500GB
Corsair 4GB Dual Channel DDR3