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Monitor will not turn on

Tags:
  • Homebuilt
  • Monitors
  • Systems
Last response: in Systems
October 18, 2009 11:23:25 PM

If any one can at all help, please do. I'm at a complete loss.

The situation is as follows:
Initially, the computer would freeze up every now and then. Then, the monitor stopped coming on when I went to boot. Every rare while I could get it to turn on, but eventually, that stopped. I could boot the computer and hear windows start and (using the windows key then u) shutdown. So I knew it was booting fully through.
I replaced the video card and the motherboard. The monitor still does not come on when I boot. I don't hear windows, because it is new motherboard with old HD, so I don't think it is booting all the way. I tried switching monitors, and same thing happened with two different monitors. Just a flashing power light like it is in standby. I disconnected the cable from the video card and the monitor told me to check signal connection (so I assume monitor and cable is good for both monitors.)
I have 2 1GB sticks of DDR2 ram. I tried pulling one of the sticks and starting it up, same thing happens. I then tried using just the other stick of ram and still no luck. While doing all this, I left the cover off to look at the internal operation. All of the LEDs on the motherboard were lit. The video card fan spun (so it is getting power) I had reseated it earlier as well as checking the power connection.
I noticed however that my cpu fan was not spinning. I then switched back to my old motherboard, connected everything, and I turned it back on. The CPU fan does not spin when power is turned on. However, when I first turn on the machine, the fan jumps a little. Same thing when I turn it off. So power is probably getting to the fan. I tried switching the connection from the 4 pin cpu fan connection on the MB to a 4 pin sys fan connection, still did not spin when I turned it on. But it has the same 'jump'. With power off, I checked the fan to make sure it wasn't bound. The fan freely spins when i move it with my finger.
I have a few guesses about the situation. Maybe my CPU overheated with a poor heat sink. I don't know though. It did not look burnt when I was moving it around. There is the small chance that both sticks of RAM are bad, but that seems unlikely. I also am a little bit weird about the whole thing since earlier it would boot to windows.
My old motherboard was ASUS P5N-E SLI. My new MB is Gigabyte EP45-UD3P. I am using Intel core 2 CPU, I forget which one. My old video card was EVGA GeForce 7900 GS. My new video card is ASUS EN9600GSO.

More about : monitor turn

a c 143 B Homebuilt system
a b C Monitor
October 18, 2009 11:56:56 PM

what OS do you have ?

have you tried another monitor ?
October 19, 2009 5:16:56 AM

Win XP; and, yes, I tried another monitor along with another cable. Both monitors did the same thing.
Related resources
a c 121 B Homebuilt system
a b C Monitor
October 19, 2009 12:36:09 PM

How about the PSU? What kind and have you tried changing it?

Try to verify (as well as you can) that the PSU works. If you have a multimeter, you can do a rough checkout of a PSU using the "paper clip trick". You plug the bare PSU into the wall. Insert a paper clip into the green wire pin and one of the black wire pins beside it. That's how the case power switch works. It applies a ground to the green wire. Turn on the PSU and the fan should spin up. If it doesn't, the PSU is dead.

If you have a multimeter, you can check all the outputs. Yellow wires should be 12 volts, red 5 volts, orange 3.3 volts, blue wire -12 volts, purple wire is the 5 volt standby.

The gray wire is really important. It sends a control signal called something like "PowerOK" from the PSU to the motherboard. It should go from 0 volts to about 5 volts within a half second of pressing the case power switch. If you do not have this signal, your computer will not boot. The tolerances should be +/- 5%. If not, the PSU is bad.

Unfortunately (yes, there's a "gotcha"), passing all the above does not mean that the PSU is good. It's not being tested under any kind of load. But if the fan doesn't turn on, the PSU is dead.
October 21, 2009 2:35:36 AM

I checked the power supply. All the voltages are good, except one of the 5V is ~4.3V where all the others are around 5.26V. I am going to replace the power supply today and also buy two more sticks of DDR2 ram just incase both of mine were failed. If anyone has any more ideas or has seen this before, please help.

Recap:
I used to be able to boot through windows, but monitor would never come on through the whole cycle.
I have tried using different monitors with same result. They work on other computers, though.
I have tried using seperate sticks of RAM to see if they were the problem, still no monitor turn on.
My motherboard and video card are both brand new just replaced. The problem existed before I replaced both of these things, and it continues to happen even after replacement.
My CPU fan does not spin, but looks like it wants to (and is not mechanically bound).

Thanks.