Bizarre monitor/display problem

I'm experiencing a problem with my computer's display which is completely baffling me.

Three or four weeks ago, I started having a problem where, while booting up, my monitor would occasionally stop displaying an image. Between certain screens the monitor would go black for a few moments (as usual), but then would not return. Instead the monitor's power light would start flashing on and off, and the screen would flash between black and off (the difference between a screen displaying an image of black and actually being turned off, or to standby). Sometime the flashing was regular, sometimes erratic. Normally there'd be about a second or so between flashes.

At first, eventually after flashing for enough time, the image would return. However, it started taking longer and longer, so I got a spare monitor, and replaced the original one, thinking this was where the problem was. Instead, the problem started occuring on the new monitor as well. It also got worse, eventually getting to the point where if the display failed, it wouldn't come back until I restarted the computer altogether, meaning it would take about 20 tries to eventually get to the Windows login screen. Once at Windows, unless I let it go to sleep or turned the screen off, it would work just fine indefinitely.

Today, after having to move the computer, I found my display was not working at all. The monitor light on the new monitor would just stay on but no picture would come, and on the old monitor the light flashed, but no picture. I thought the problem with was the graphics card, so I replaced that too, but it didn't help. Strangely, when I try plugging into my TV (which has a PC input), it works absolutely fine. I'm also having difficult ascertaining whether or not the monitors themselves are broken, as I don't have any other way of testing them. It seems unlikely that both would simultaneously break in the same way without some common cause (when I plugged the spare monitor in, it was the first time I'd used it, haven gotten it from somewhere else).

Having now tried three monitors, the TV being the only one to work, two monitor cables, two graphics cards (both of which have been tried in two different PCI-E slots), two monitor power cables, and multiple mains sockets, I'm totally baffled, and it's not even clear to me where the problem lies. Any light that could be shed on this, I'd be extremely grateful.

Im not exactly sure what information is relevant to this problem, so ask and I'll try to answer.

 

I had a problem with my display while setting up my current PC.

I returned 3 monitors, and also tried another Graphics card, then someone i know who is totally uesless on the PC, told me to try a different cable, so i did, and BAM everything worked! I think it's worth a try if you haven't already.

Could you try using the onboard video from the motherboard?

And can you please post entire system specs, including Power supply?

 

Thanks for the fast responses.

Burrell, sorry it may have got lost in the huge initial post, but I have already tried two monitor cables. Also the TV screen actually DOES work. It's possible that it's experiencing some variation of the original problem, but if so it's able to deal with it very quickly and effectively. I've only started using the TV screen today, the other two screens I used a couple of weeks earlier. Also, the motherboard has no onboard video.

plodr, the problem starts during boot, long before actually getting to Windows, so I don't see how safe mode could help. If you still think it's worth trying, instructions on booting to safe mode without any visuals would be helpful. The other suggestions could also be true, if there are ways to diagnose or rule these out, let me know. The TV that I'm using has the same input socket as a monitor, so it's designed to double as a computer monitor, I'm not using some other form of input.

As for specs, the current video card is an NVidia GeForce GTS 250, the old one was a 8600GTS 512MB. Motherboard is an Asus P5KC. Not sure what other details you want, if there's anything specific then let me know.

 

Not me, but this was made by someone who does know what they are doing, this methon requires a voltmeter, you could do a less thourough test by checking the voltages via the BIOS hardware monitor.