Computer doesn't boot

Most times, I can figure out what is wrong with a computer. This computer turns on, the power supply has tested ok. But the fans are running fast from the start, the switch doesn't work, you don't get a POST screen, the hard drive isn't active loading things like it should. The CD drive is powered. I tried another switch, with the same results. I pulled tried to boot to each of the RAM sticks only, same thing.

I think I've narrowed it down to the Motherboard or the CPU. I doubt two sticks of RAM are going to go bad at once. It's certainly not the hard drive causing this problem. It still should POST. I reseated many of the connections, including the CPU. And I pulled the CMOS battery for a few minutes.

From your experience what would you think that is bad in this machine? The CPU or the Motherboard? I think it's one or the other.

Troy

reply to post by cybertroy

It could be your power source that's being a drag, you might need to switch it out with a quality one.

Same thing has to be done if you're upgrading video cards or even ram.

not enough power, not enough power to the video card or ram, and the thing flunks out.

EDIT: nevermind, I read your power source is ok.

It could be your video card. Sometimes it just burns out.




[edit on 27-4-2009 by star in a jar]

[edit on 27-4-2009 by star in a jar]

It could be the power supply, even if some things are powered it does not mean that the power supply can supply all the outputs, and if the power to the CPU is not working then the CPU will not work.

And you can try switching the computer on without any memory or video card, it should at least start the initial test and beep when it finds that some things are missing. If it does not then it's the CPU or the motherboard.

If you don't see your POST screen your BIOS is not initializing. You actually only need a few things hooked up to see the POST screen. Try removing the following:

All RAM - You don't need RAM for the POST screen
All drive cables going to the mainboard and the power cables for them
All card devices except the video card)

Basically have only the mainboard powered, cpu installed and a video card. Nothing else. No mouse or keyboard plugged in either. If this doesn't work try it with another video card.

If you still can't see anything at the POST screen find out where your clear CMOS jumper is on the mainboard (it should be marked on the board and near your battery) the battery removal probably won't work. Unplug your power cord and leave your power supply on. Press the power button to discharge the capacitors on the board. Then move your jumper and move it back.

Were you trying to overclock something in the BIOS? Please let us know what you were doing prior to this.

This is a Compaq. I don't think the owner made any modifications. It's only 2 years old.

There was a power failure at his house recently. He had surge protector, but I guess that doesn't guarantee problems cannot occur.

The fact that there isn't a POST screen, the power button will not power the machine on or off leads me to think there is something odd going on with the board, but let me try another video card, to see if I can get something on the screen. I wanted to try a different card earlier, but I didn't think I had a PCI video card until I was checking out another machine I have in here. I definitely don't have an extra PCI-E card.

Well, no video or POST with a different card. No POST or video with no RAM or drives connected.

It acts like it checks the DVD drive and the hard drive.

That's interesting, I could power the machine on, with the switch, with the BIOS battery out, but I couldn't power it off. Could BIOS be messed up? It looks like it has a replaceable BIOS chip. I'm going to leave the battery out for a while.

(update) And, a different (good) power supply doesn't help. Leaving the battery out doesn't help. It only allowed me to power on the computer with the switch., not off.

Troy




[edit on 27-4-2009 by cybertroy]

[edit on 27-4-2009 by cybertroy]

Computers have a soft power button now which means the mainboard is powered all of the time and the switch doesn't physically turn power on/off. That's why you need to hold the power button in for 5 seconds to do a hard shutdown.

I have seen bad boards not display the POST screen and look like the CD/DVD drives are initializing but that is just the drives flashing when power is supplied to them not the BIOS working.

If you eliminated the video card and power supply out of the equation the only 3 things left that could be causing this are:

1. CPU
2. Mainboard
3. Your display device (monitor, etc... not likely)

You might be SOL - no POST is bad and if you have cleared the CMOS jumper and reset the BIOS that eliminates a bad/corrupt BIOS config that would cause this.

From my experience mainboards will usually die before processors. If I were to choose one I would say replace mainboard.

It's definitely not the monitor. And the hard drive activity for the most part has stopped, during a period of time where it should be loading the OS.

Yes, I've seen Motherboards go bad more often as well. I just don't have the physical signs like swollen capacitors, which really helps you say, "yes, that's what it is." I just wanted to check and see if somebody had some wisdom to impart on a similar situation.

I have a PC analyser, but I struggle with trying to understand the manual and how to use it. I need to invest in a better, more user friendly one.

Thanks for your input my friends. I'll throw he motherboard replacement idea out there for the owner of the computer for consideration.

Troy

Originally posted by cybertroy

It acts like it checks the DVD drive and the hard drive.

As mentioned by a previous poster, unplug all non-essential equipment.

The DVD and the hard drive should not be plugged in.

Lost count the the number of times I've had the following conversation.

Power surge.
No boot.
Nothing works.
Tried everything.

Did you unplug the cd/dvd?
No. Why would I do that?
Unplug it.

HEY! It booted. Thanks man.

Now shut it down and plug the cd/dvd back in and boot.
OK, it booted fine again.
How did you know?......

Barring that, here are some troubleshooting charts to follow.

Power supply and instructions.

Video Card

Oh, hell. I'm not going to link them all. :bnghd:
Look at the links on the bottom of this page for the rest of the troubleshooting charts.

Best of Luck
makeitso





[edit on 4/29/09 by makeitso]

This is a motherboard or CPU problem, I'm pretty sure. I've tried numerous things, including another video card and many things disconnected.

The strange power button problem, along with the "no POST," and the fans running high speed from the beginning helps solidify this. You cannot shut down the machine at all with the power button, even by holding it down.

I was mainly trying to see if anyone had this same problem, or similar. I mainly wanted to rule out the CPU or the motherboard.

I think I'm just going to put in a micro ATX board that will fit the case, and work with the AMD processor it has. And slap on Windows XP in place of the Vista that it came with.

I tried bidding on a matching board on E-bay, but it went above $100. I think I can do better on the price at Tiger Direct for a new board, and give this guy a quicker system than Vista. He likes XP better anyway.

Troy

pull the CPU and smell it. does it smell burnt.

AMD CPUs run hot and if something stops the fan or the computer case gets hot inside for to long.

always put a large CPU fan on a AMD CPU.

After reading all posts in thread, I'd bet mainboard, not CPU... and the reason is the no power off problem. If you're sure the power supply checks out, that problem would be more indicative of mainboard failure, not CPU failure. I see more MB's go than CPUs as well, as long as no overclocking was involved.

I agree with the majority and go with the motherboard. Ive been down this road before, a power surge smoked the mother board.

It was the motherboard. After I put in a new Asus board, and a higher output power supply, I was good to go. A larger supply was recommended for the new board.

The most fun part was reworking the plug for the power switch, and the front LEDs. Some of that was just a matter of moving some of the connections inside the plug. The plug wasn't long enough to cover all the needed pins, so the two power switch connections had to be connected outside the plug.

Does anyone know if you can just buy these plugs? For future reference. What else would you call them? Connectors maybe? It's pretty much those small plastic connection boxes that a bundle of wires go into, and then slides down onto the pins on the motherboard.

It all worked out ok. He's got a potentially better machine, but it's housed in a Compaq box. He could make a pretty good little beast out of the machine if he decided to upgrade. Thank goodness these companies follow standards, the fit was pretty much perfect.

Troy