Computer won't turn on

[jtrory]

Hi all,

I'm looking for some help with my computer, which will not power on. For several weeks, before this happened, turning my computer on would take several attempts - the first couple, the lights and fans would come on for a split second and then die. After a few tries it would boot up.

Now, my computer just won't turn on at all. No lights, no fans, nothing. I've unplugged IDE cables, used every outlet in the apartment, checked connections and switched cables, and nothing! There is no light on the mobo, and the PSU makes a weird sound when it's own power switch is turned on and off, which is why after some consideration I determined that the PSU was the problem.

Problem is, I just received a new PSU from Newegg, and it doesn't work either. I can't figure this out. I thought maybe it was the power switch itself on the tower, but I can't see well enough inside the case to tell if a connection is broken.

So, I'm at a loss. I don't know what to do, without having to spend a considerable amount of money either getting it professionally fixed, or worse still, replaced.

Most of the hardware inside the computer is new within the last 2-2/12 years, so I don't see why it should be the mobo or CPU. The only thing that could be considered old is the PSU, which is again why I figured that that was the issue.

Thanks for any help!

 

[jj555298]

I've had the same problem before, random reboots for a few days then it would come on for a minute then seconds. It ended up being the power button and it could very well be your problem especially if it's a cheap case. To check this you can open up your case and unplug the power button from your mobo, very carefully take a screwdriver in between the 2 prongs and that should turn your PC on. Do this at your own risk though, I've done it plenty of times just don't hit anything else with that screwdriver.

 

[jtrory]

I tried this with both the old and new PSU's, and still nothing. Is it just the power button switch I need to unplug, or the reset and LED as well? I just unplugged the power cable as you suggested. I also tried moving/removing the RAM, and again, nothing. Maybe Newegg send me a DOA PSU? I don't hear anything when I turn the on-board PSU power switch on, like I used to with the old one.

 

[jtrory]

I stripped the whole thing down to just the mobo, and still nothing with either PSU. What does that mean?

 

[jj555298]

Sorry for the late reply, if you're still following this the next step would probably replacing the mobo. Before you do that test out the PSU's on another PC if you have one around, another idea would be to take it to a local shop many offer free diagnostics. I've had some mobo's die on me shy of one year, you never know.

 

[jtrory]

Okay, so it turned out not to be the PSU. The CPU somehow got damaged, and I'm pretty sure it damaged the mobo too. So I replaced both.

Fixed! Well, kinda.

Now I get no video. The computer powers on fine, but my monitor is blank. I tried reseating the video card (nVidia 7600GT), unplugging and replugging the cables etc. Next is to check and maybe reset the CMOS.

Also, I'm hoping I didn't screw up and get the wrong mobo that doesn't support my RAM and/or GPU. I bought an ASUS M3A78-EM.

Now, the memory standard is DDR2 1066 and I have DDR2 800, but I did research before buying and discovered that supposedly if I have under 1066 it shouldn't matter, so long as it's DDR2 and not over 1066. And, my video card is PCI-e 1.0 and the mobo is PCI-e 2.0, which is meant to be backwards compatible so that shouldn't matter either.

But, as of right now, I have to video so something weird is going on somewhere.

 

[jj555298]

A bad PSU or power surge can sometimes damage multiple components, maybe it fried your video card too? And you're right about the ram and video, it's all compatible.

 

[jtrory]

Well, here's two things I discovered after some more testing that don't make much sense.

1) The PSU that I thought was "bad" and the cause of all my problems appears to be just fine. Unless there was a power surge that damaged everything on the mobo but did not damage the PSU, but that seems odd. I would think the PSU would be screwed too.

2) Also, the new mobo has a built-in video processor, and I tried plugging the monitor into that and still no display. Which makes me think that it's not the GPU after all, but perhaps something to do with the monitor or the cables. The monitor does have power, because the power light is on and it reads "No Signal".

So I'm really stuck.

 

[jj555298]

Well as I said earlier in the thread it's most likely the mobo or cpu, I'm wagering that it's the mobo. You can also try different ram, use one stick try it in both slots etc.
I should have asked before but what are you full system specs? Troubleshooting can be a real pain.

 

[jtrory]

The CPU and mobo are both brand new, I just replaced them because the old ones were fried, causing my computer not to power on at all. Now that the power thing is fixed, I just don't get anything on my screen, which I'm starting to think is a POST error.

I also got a new stick of 2GB RAM to go with the one I already had, and have tried just the new stick on it's own (since it shouldn't be damaged), and again that hasn't solved the problem. Neither has moving the 2 sticks around the 4 slots on my new mobo.

I should also mention that I tried removing the GPU and using only the onboard VGA to at least try and get to BIOS, but that didn't work.

My specs are:

ASUS M3A78-EM motherboard
AMD Athlon 64 X2 7750 Kuma 2.7GHz Socket AM2+ 95W Dual-Core black edition
4GB (2x 2GB) G.Skill DDR2-800 RAM
GeForce 7600GT video card
120GB HDD
Sunbeam PSU-BKS580-US 580W ATX Power Supply

 

[Guest]

Your old Nvidia video settings are saved on the old hard drive. You need to go into windows in safe mode or VGA mode (hold down F8 key during boot for this option) and then uninstall all Nvidia drivers and software. boot back in normal mode (screen will look ugly) and download and install latest nvidia drivers... reboot again and set resolution back to normal

 

[jtrory]

But I get no display on my screen, so how do I get into the BIOS?