Computer won't boot

[viggoo]

When I start my computer everything but the CPU fan starts as normal, and the screen remains blank. I hear the hard drives activate as well.

I've tried the two 4-pin connectors that fit the fan power, but noen of them work.
I have another connector with 3 pins, and when I connect the fan to that the fan starts up, but the screen is still blank. As the power remains on i keep hearing the faint sound of a reset (I don't know if this makes sense, but it's like a beep, but not a diagnostic beep from the mobo).

I guess this rules out the CPU fan being the culprit, but I'm thinking it might be the CPU, the PSU or the mobo.
Anyone got an idea? Thanks in Advance!

Hardware:
PSU: Mist 500 W
RAM Geil 2GB (2x1GB) DDR2 PC6400 800MHz
HK: Gigabyte GA-P35-DS3P
CPU: Intel Core 2 Duo E6750 with stock fan
GPU: Gigabyte ATI Radeon 5450 Silent (I think)
Plus a DVD-reader and 4 SATA hard drives

 

[Harvey]

Have you tried unplugging and reseating your RAM and vid card (and any other plug in cards)?

 

[viggoo]

Have you tried unplugging and reseating your RAM and vid card (and any other plug in cards)?

Yeah, I've removed the PCI-cards, tried both RAM-sticks alone, removed and reseated the video card, checked the different power connectors from the PSU to the mobo...
After I started the computer again I'm noticing I get the faint reboot beeps even when the CPU-fan doesn't spin up.

 

[WoodButcher]

Reseat the monitor end of the vid cable? All cables in the PC? Are you getting the bios beep to begin with?

 

[viggoo]

Reseat the monitor end of the vid cable? All cables in the PC? Are you getting the bios beep to begin with?

Tried switching out the video cable, but no luck.
And no BIOS beep on startup.

 

[pcgeek11]

Reset the BIOS using jumper or pulling the battery. If no good I would say Motherboard.

 

[viggoo]

Reset the BIOS using jumper or pulling the battery. If no good I would say Motherboard.

Tried pulling the battery to reset BIOS, with no result.
As some stuff definitely is getting power, can I rule out the PSU being to blame? Or could the PSU have one of the connectors (e.g. the 4-pin PSU connector) be bad, and the others still working?

 

[GTSRguy]

i would not rule out PSU yet, it could very well be the problem. I dont think the monitor is the problem, because there is no POST beep.

I found this, a list of things your computer must do to pass POST.

Each time the computer boots up the computer must past the POST. Below is the common steps a POST performs each time your computer starts.

1. Test the power supply to ensure that it is turned on and that it releases its reset signal.
2. CPU must exit the reset status mode and thereafter be able to execute instructions.
3. BIOS checksum must be valid, meaning that it must be readable.
4. CMOS checksum must be valid, meaning that it must be readable.
5. CPU must be able to read all forms of memory such as the memory controller, memory bus, and memory module.
6. The first 64KB of memory must be operational and have the capability to be read and written to and from, and capable of containing the POST code.
7. I/O bus / controller must be accessible.
8. I/O bus must be able to write / read from the video subsystem and be able to read all video RAM.

If the computer does not pass any of the above tests, your computer will receive an irregular POST. An irregular POST is a beep code that is different from the standard one or two beeps. This could be either no beeps at all or a combination of different beeps indicating what is causing the computer not to past the POST.

 

[Harvey]

Fans spinning, but no beep or anything else sounds like the motherboard or the CPU. I've seen it both ways.

 

[WoodButcher]

As some stuff definitely is getting power, can I rule out the PSU being to blame? NO! Or could the PSU have one of the connectors (e.g. the 4-pin PSU connector) be bad, and the others still working? Entirely possible,,,

Have you another PSU available to swap? You could also buy a tester for the PSU, I got one from radioshack but I have read that a multimeter is better.

 

[viggoo]

i would not rule out PSU yet, it could very well be the problem. I dont think the monitor is the problem, because there is no POST beep.

I found this, a list of things your computer must do to pass POST.

Each time the computer boots up the computer must past the POST. Below is the common steps a POST performs each time your computer starts.

1. Test the power supply to ensure that it is turned on and that it releases its reset signal.
2. CPU must exit the reset status mode and thereafter be able to execute instructions.
3. BIOS checksum must be valid, meaning that it must be readable.
4. CMOS checksum must be valid, meaning that it must be readable.
5. CPU must be able to read all forms of memory such as the memory controller, memory bus, and memory module.
6. The first 64KB of memory must be operational and have the capability to be read and written to and from, and capable of containing the POST code.
7. I/O bus / controller must be accessible.
8. I/O bus must be able to write / read from the video subsystem and be able to read all video RAM.

If the computer does not pass any of the above tests, your computer will receive an irregular POST. An irregular POST is a beep code that is different from the standard one or two beeps. This could be either no beeps at all or a combination of different beeps indicating what is causing the computer not to past the POST.

Thanks for that great list! The faint "reset beep" I keep hearing could indicate a problem with steps 1 or 2. I think I'll get my parents to bring their PC over here, so I can try its PSU Like WoodButcher suggests.

If that doesn't work I guess it's gotta be the motherboard or the CPU, in which case I'll probably switch them both out anyway. Or is it worth it investing in a new LGA775 Socket CPU or mobo?

Thanks a lot for the help guys, it's greatly appreciated