Computer won't POST. How do I go about trouble shooting?

[Connerd117]

A couple of years ago I purchased a pre-built computer from a local computer repair store. It worked fine, but as you can imagine it was a little slow for the price I paid. Fast forward a year or so and I decided to build my own PC. After I got this new machine up and running I decided to connect the old pre-built, along with a low end graphics card with an HDMI out to my TV and use it as a media PC. This is working great until a few days ago when I go to turn it on. The fans all spin up, but no picture is ever displayed on the monitor and the front I/O lights on the case do not turn on. The only way I am able to turn off the machine is to unplug it or flip the power switch on the back of the power supply.

Following this I try to trouble shoot. I try taking the video card out, no change. I try a different monitor, still no picture displayed. I try each of the four sticks of ram individually, no change. I tried using the jumpers to reset CMOS, no change.Seeing as I have no other motherboard that can fit the CPU, not other CPU that can fit in the motherboard and no power supply that is not currently in use I am wondering if there is anything I can do short of buying more hardware at random to find out what isn't working.

Computer Specs:

Motherboard: ASUS M3A78-CM

CPU - AMD something (I forget which one)

PSU - Nspire psp-575s2

Video Card (removed) - Sapphire 5670 512 MB

[Drethstoff]

Do you have the little internal speaker connected? If you do what are the beep codes its giving off? One short beep means that it is posting fine.

[CaptainSi]

You may need to flash your BIOS with the current version. Check the power connectors in the mobo are seated correctly.

[CaptainSi]

And replace your CMOS battery.

[Connerd117]

I did put a motherboard speaker from my other computer in it and it never gave off any beep codes. The only action the computer makes when powered on is running the fans. And I don't think I can update BIOS if I cant even get to the POST screen. As for the CMOS battery, is that a special battery, or just one of those watch batteries I can get from any store?

[IzzuddinFX]

Did you remove your motherboard from your case recently?

[mgsstar]

I did put a motherboard speaker from my other computer in it and it never gave off any beep codes. The only action the computer makes when powered on is running the fans. And I don't think I can update BIOS if I cant even get to the POST screen. As for the CMOS battery, is that a special battery, or just one of those watch batteries I can get from any store?

Yes it is just a normal battery replace with the battery that corresponds to your motherboard battery model #.

[Connerd117]

Did you remove your motherboard from your case recently?

No, I hadn't touched it for a month or so, and when I tried to turn it on it just wouldn't boot.

[Connerd117]

I did put a motherboard speaker from my other computer in it and it never gave off any beep codes. The only action the computer makes when powered on is running the fans. And I don't think I can update BIOS if I cant even get to the POST screen. As for the CMOS battery, is that a special battery, or just one of those watch batteries I can get from any store?

Is this the problem though? When I searched it looked like if the CMOS battery died the computer would still boot. Mine doesn't even power on the front I/O lights on the case...

[IzzuddinFX]

Did you remove your motherboard from your case recently?

Recheck all wire and connector, 8 pin, 24 pin, gpu power connector, HDD power and sata, and the last thing, double check if there is misconfigure at the front panel connector...