PC has no visual output

[Cheezzhead]

Hi guys, I don't if this is in the correct forum, if not just move it to the right one.

I own a 'homebuilt' PC since about 1.5 years; originally, I selected my own components and the pc was prebuilt at a company then sent to me as a full package, but since then I've added my own network cards, RAM sticks and SATA, as well as rewiring some cables (it was pretty mediocre when I received it).

Specs:
Mobo: ASRock 890FX Deluxe4
CPU: Phenom II X6 1055T
CPU Cooler: CoolIT ECO A.L.C.
GPU: Sapphire Radeon 5870HD
RAM: Corsair XMS3, 1333 MHz 2x4 GB
Case (if necessary): Cooler Master CM 690 II Advanced

Currently, my PC passes POST as far as I know, but it shows no visual output. When turned on, the GPU fan spins loudly (100%) which, in my limited knowledge, indicates that the mobo isn't regulating the speed. The mobo then gives out a beep code (1 long and 8 short), while the POST code indicator on the board indicates "2E" (which is when it "initializes all the output devices"). It continues running through the checkpoint until it finishes POST (giving out one short beep as per usual). I assume that it then continues booting up only I have no screen.

I've been having a problem with my PC for a while now: for almost half a year, I had to reset the PC twice (always) until it would succesfully boot up. The failed two attempts would not have any beep codes or other indications of POST failure. I regret now that I never checked out the code checkpoints on the motherboard. Of course, I was too lazy to do anything about it since technically, it was able to boot correctly.
I recently turned on my PC from sleep-mode state (it was in sleep mode for almost 2 days due to some real-life happenings) and it first showed the current problem: GPU fan spinning at 100% and no visuals.

Since then, I was able to succesfully boot the computer after disconnecting every device, including all my HDD's, all but one of my RAM sticks, my network card and my CD drive. I attributed the original problem to my network card which had also been showing problems for a while now. When I used a different PCIe slot it worked fine, along with all my HDD's and RAM sticks reattached. So basically, my PC booted normally with everything connected.
This was about 2 days ago. I continued to experience the same problem (GPU fan, no screen, etc) and I would turn off the PC, turn off the PSU switch, unplug the cable, then replug it, turn on the PSU switch and the PC would work fine again.

Yesterday the problem reemerged after, again, rebooting from sleep mode. Only this time, nothing I do makes the PC work - I've disconnected all external devices but to no avail. I've reseated the GPU and it didn't work either. I even took out the fan controller because it had loads of cables and I read somewhere that wires touching both the mobo and case can cause shorting. Nothing as of yet.

The only realistic option is that my PSU is broken, but since it did manage to boot several times in the past few days, I'm hoping that there's another solution that would solve this. Any help would be appreciated.

Other things I've tried:
- Reset CMOS using the clearCMOS button on the mobo.
- Took out and reseated the Motherboard battery to reset BIOS
- disconnected all HDDs, network cards, external cables and cd drives, then tried 1 RAM stick in each of the four DIMM slots.
- starting without any RAM sticks gives the standard long beep codes (which means the memory isn't faulty as far as I know)
- checked all cables
- made sure the motherboard wasn't touching the case anywhere, also made sure no cables that aren't intended for the mobo don't touch the mobo and case simultaneously (only did this because I couldn't think of anything else).

 

[COLGeek]

You likely have a defective (failing) PSU or GPU. Do you have access to another PSU and GPU that you could swap for troubleshooting?

 

[Cheezzhead]

Hi COLGeek, thanks for the quick reply. I had already tested out an old PSU which didn't resolve the problem. Hadn't thought about a GPU though, because I was certain (read: hopeful) that it wasn't defective.

I've tested out an old 8800GT and the system boots normally. Problem is that the 8800 has some problems of its own; I get visual output but it's contorted and very hard to read. But at least I can see the screen. I think I can get a better GPU if you need me to do something on the PC.

Is there anything to be done or does this just mean I have to replace my current GPU? I initially thought the symptoms pointed to something else than a defective graphics card, and it still seems weird to me that this isn't caused by the motherboard side of things.

 

[COLGeek]

The HD5870 can be rather picky when it comes to PSUs. What make/model are you using? Unfortunately, they can and do become defective. Have your tried the HD5870 in another system to see it works elsewhere?

 

[Cheezzhead]

Ah sorry, forgot to add the PSU to my specs. It's a GX 750W from Cooler Master. Unfortunately, I don't have a working system at my disposal right now.

 

[COLGeek]

Your PSU should be fine as long as it is working properly. PSUs can and do wear out. Do you know how old it is?

 

[Cheezzhead]

It's relatively new; I already had it replaced last summer. Just like the GPU, which was replaced shortly after that (the problems were connected, or so the factory told me). This is also one of the reasons I can't believe it's defective again - and if it is, that there could be an underlying problem. Because 3 defective components within the year just seems like a streak of impossibly bad luck.

 

[COLGeek]

When a PSU fails, it is fairly common for them to take the GPU with them. GPUs are particularly sensitive to power issues.

Based on what you have posted, it seems that your PSU is likely ok. That leaves the GPU. Since swapping to partially operating 8800 "worked", then I am more convinced that your GPU has an issue.

 

[Cheezzhead]

"an issue" meaning I will have to replace it? Argh, not again :<

 

[Cheezzhead]

Best answer selected by Cheezzhead.