Sign in with
Sign up | Sign in
Your question

Computer boots, but no video

Last response: in Graphics & Displays
June 1, 2011 12:48:51 AM

Sorry if I posted this in wrong section..

ok so here is my hardware
Mobo: Gigabyte P55-A-UD4P
CPU: i5 750
Video Card: PowerColor 5850
Ram: G.Skill ripjaw ddr3 1600
PSU: Corsair TX 650W

So here is my problem, a couple days ago I try to boot my computer. Computer boots, but bios makes beeping noise and no
video output. I looked up the beep codes, and it referred to video issue. I fiddled around with it for about an hour, couldn't get it working... I blew out all of the dust in my computer.. still wouldn't work, I then discovered there was a rear vent on my video card and it was full of dust. Blew it out, then it booted fine.

Computer worked great for about 5 days, then yesterday same issue happened. Tried a ton of things nothing worked.
however the computer DOES boot into windows (with no video) as I can access shared folders from my revo box.

I then did these steps

1) Replace video card with a PowerColor 3450. Computer boots fine into windows WITH video.. so working perfectly... But I obviously don't want to use that card as my main card.. Ok that confirms it.. video card must be dead... no problem

2) Bought a new video card EVGA 560 ti... hook it up... no boot. No bios beeps, however this time computer does not even make it past POST.

3) Ok maybe psu is dieing and isn't suppling enough power to these more powerful cards, go out and buy a OCZ modxstream 700 watt. No go. Try it with above combinations, with the same results.

Now I guess there is a chance the brand new video card is bad or the new power supply, but kind of doubt it. Could it be that it is a motherboard issue and for some reason it not working with the faster video cards? I just don't understand why it would boot fine with 3450 but nothing else.
Any ideas?

More about : computer boots video

a b U Graphics card
June 1, 2011 1:23:49 AM


The fact that with the 560 it doesn't even POST is very odd. Could suggest a dying PSU but if your 700 watt doesn't fix it, then I would suggest a dying motherboard.

Had your compy been having issues past POST, like in the windows startup, I'd say that maybe it'd be a driver conflict because you're going from ATI to an Nvidia card. However if the problem's in POST, then that can't be it. OR, you just HAPPEN to get a bad power supply again from OCZ, I highly doubt it.
a b U Graphics card
June 1, 2011 1:29:43 AM

Time to start troubleshooting.

Work systematically through our standard checklist and troubleshooting thread:
I mean work through, not just read over it. We spent a lot of time on this. It should find most of the problems.

If not, continue.
The following is an expansion of my troubleshooting tips in the breadboarding link in the "Cannot boot" thread.

I have tested the following beep patterns on Gigabyte, eVGA, and ECS motherboards. Other BIOS' may be different, but they all use a single short beep for a successful POST.

Breadboard - that will help isolate any kind of case problem you might have.

Breadboard with just motherboard, CPU & HSF, case speaker, and PSU.

Make sure you plug the CPU power cable in. The system will not boot without it.

I always breadboard a new build. It takes only a few minutes, and you know you are putting good parts in the case once you are finished.

You can turn on the PC by momentarily shorting the two pins that the case power switch goes to. You should hear a series of long, single beeps indicating memory problems. Silence indicates a problem with (in most likely order) the PSU, motherboard, or CPU. Remember, at this time, you do not have a graphics card installed so the load on your PSU will be reduced.

If no beeps:
Running fans and drives and motherboard LED's do not necessarily indicate a good PSU. In the absence of a single short beep, they also do not indicate that the system is booting.

At this point, you can sort of check the PSU. Try to borrow a known good PSU of around 550 - 600 watts. That will power just about any system with a single GPU. If you cannot do that, use a DMM to measure the voltages. Measure between the colored wires and either chassis ground or the black wires. Yellow wires should be 12 volts. Red wires: +5 volts, orange wires: +3.3 volts, blue wire : -12 volts, violet wire: 5 volts always on. Tolerances are +/- 5% except for the -12 volts which is +/- 10%.

The gray wire is really important. It should go from 0 to +5 volts when you turn the PSU on with the case switch. CPU needs this signal to boot.

You can turn on the PSU by completely disconnecting the PSU and using a paperclip or jumper wire to short the green wire to one of the neighboring black wires.

A way that might be easier is to use the main power plug. Working from the back of the plug where the wires come out, use a bare paperclip to short between the green wire and one of the neighboring black wires. That will do the same thing with an installed PSU. It is also an easy way to bypass a questionable case power switch.

This checks the PSU under no load conditions, so it is not completely reliable. But if it can not pass this, it is dead. Then repeat the checks with the PSU plugged into the computer to put a load on the PSU.

If the system beeps:
If it looks like the PSU is good, install a memory stick. Boot. Beep pattern should change to one long and several short beeps indicating a missing graphics card.

Silence, long single beeps, or series of short beeps indicate a problem with the memory. If you get short beeps verify that the memory is in the appropriate motherboard slots.

Insert the video card and connect any necessary PCIe power connectors. Boot. At this point, the system should POST successfully (a single short beep). Notice that you do not need keyboard, mouse, monitor, or drives to successfully POST.
At this point, if the system doesn't work, it's either the video card or an inadequate PSU. Or rarely - the motherboard's PCIe interface.

Now start connecting the rest of the devices starting with the monitor, then keyboard and mouse, then the rest of the devices, testing after each step. It's possible that you can pass the POST with a defective video card. The POST routines can only check the video interface. It cannot check the internal parts of the video card.
June 1, 2011 2:00:23 AM

Hi jsc, I read through your link. About 1/2 of it is regarding new pc builds, and the other 1/2 I followed to the T many times and still no luck.
I do see near end of your post "or rarely the PCIe interface" that's what I'm thinking it might be, although still does work with the 3450 PCIe card

I never take computers to pc repair shop, but this is one time I just might have to since I have no spare motherboard or cpu to test with