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I'm stumped.

After 18 months of rock solid stability. My display started flickering and buzzing a couple months ago. More specifically, I am seeing horizontal light colored lines flickering like an old TV. If I left the computer on, as I normally do, I would eventually lose the signal to the monitor completely.

I changed the graphics card, power cords, monitor, display cable (tried digital and analog). No effect.

I tested the power supply and viola! It failed. I got an RMA from Corsair (excellent support) and a new 620 watt in place of my old 520 watt psu. No effect. Argh!

But! I noticed two new clues when I installed the new power supply.

1. The issue goes away if I do not connect the case fans. Antec 900, with 4 case fans. Note: the large 200mm fan on the top doesn't seem to affect it. I tried connect each of the case fans independently and in different combinations and could not isolate a single fan problem. Problem is, I want that cooling and I want to know what changed.

2. The flickering seems to go away and the loud buzzing reduces to 10% of the volume if I crank up the monitor's brightness to 100%. Weird.

Ideas? Recommendations?

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Last Post by donaldw
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Update: I no longer get normal function if I disconnect the case fans.

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Is everything properly grounded?

Try plugging your display into a different wall socket than your machine (not a different outlet on a power strip or the other outlet in the same wall-box, but another wall-box altogether, maybe even on another circuit).

It sounds like the capacitors that feed the display controls aren't getting charged up properly and it's screwing with the output. At what kind of rate is the flicker?

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By the sound of it you are getting interference from the fans, you can sometimes see this happen when you get a vacuum cleaner close to a TV set. Speak to a service technician about the possibility of a "noise suppressor" (I think it is called) to be fitted on the fan power supply. I don't know if it can be done to a PC but I know you can do it to a vacuum cleaner and other electrical appliances.

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By the sound of it you are getting interference from the fans, you can sometimes see this happen when you get a vacuum cleaner close to a TV set. Speak to a service technician about the possibility of a "noise suppressor" (I think it is called) to be fitted on the fan power supply. I don't know if it can be done to a PC but I know you can do it to a vacuum cleaner and other electrical appliances.

Good idea, but OP shouldn't need to pay a technician to do that. Most display cables have built in noise filters from the OEM which should catch most, if not all, of that. To be extra vigilant about noise, you could slap a ferrite filter on/in line with the fan cables. DigiKey or RadioShack should have those for pretty cheap. Google "clamp on ferrite".

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Thank you for that donaldw, I thought it could be done, I just did not know that they were available like that.

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Is everything properly grounded?

Try plugging your display into a different wall socket than your machine (not a different outlet on a power strip or the other outlet in the same wall-box, but another wall-box altogether, maybe even on another circuit).

It sounds like the capacitors that feed the display controls aren't getting charged up properly and it's screwing with the output. At what kind of rate is the flicker?

Thanks. I tried plugging the display into a completely different outlet to no affect. There was no change in outlet or anything. I'm pretty convinced it has to be component failure of some sort. What would happen if those capacitors are bad?

I'm not sure how to describe the flicker rate. It's quite fast. 4-8 flickers per second perhaps? It reminds me of what a display looks like in the old days when you chose an incorrect synch rate.

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I've got a thread going in the monitors forum about one of our work LCD monitors and what happened after a partial power failure (running on single-phase for a while), then total power failure, then power restoration. If you're mechanically inclined and your monitor isn't under warranty, you could consider tearing it apart to see if any of the caps look swollen or if anything else is fried.

Before you do that though, consider hooking the display up to a different PC as well as hooking up your PC to a different display to see if you can narrow down where the problem is coming from.

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Good idea, but OP shouldn't need to pay a technician to do that. Most display cables have built in noise filters from the OEM which should catch most, if not all, of that. To be extra vigilant about noise, you could slap a ferrite filter on/in line with the fan cables. DigiKey or RadioShack should have those for pretty cheap. Google "clamp on ferrite".

Is this noise something that would build up over time? I ran this configuration for over 18 months without a single glitch. The change was sudden and drastic.

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I've got a thread going in the monitors forum about one of our work LCD monitors and what happened after a partial power failure (running on single-phase for a while), then total power failure, then power restoration. If you're mechanically inclined and your monitor isn't under warranty, you could consider tearing it apart to see if any of the caps look swollen or if anything else is fried.

Before you do that though, consider hooking the display up to a different PC as well as hooking up your PC to a different display to see if you can narrow down where the problem is coming from.

Thanks. I have a spare working display. No change. I also used the original display on another system and it works perfectly. I also tried new cables, analog and digital, and I installed a new video card.

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The parts I haven't changed:

Mobo
Hard Drive
Case Fans
Case
Processor
Ram


All temps are low and looking fine.

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I am not an electrician but I assume that noise suppression is a normal configuration of all motherboards and I would guess that it is now faulty in yours. A new motherboard would/should fix the problem but so should the new cables.

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Great! Sounds like there's no need to tear into the monitor, at least. That is bizarre though. Try firing it up briefly with no fans or the bare minimum fans to keep it from cooking and see if that restores a flicker-less display. Disconnect the fans from the headers on the mobo (do you monitor fan RPMs? are they running in the proper direction and getting proper feedback?).

Have you added any new RF emitters around where your PC is? New cell phone/PDA/WiFi, etc. Put any new appliances in your living quarters that could possibly be on the same circuit? Any wiring changes in your building? Maybe take a multi-meter and check your outlets to make sure they have the right output, make sure that they are grounded properly, make sure that neutral and ground are properly bonded, etc. Check that your PC case is in common with ground. I'm kind of grasping at straws now :?:

If the fans were going to introduce enough noise to cause problems, I would have guessed you would have noticed it long ago.

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Great! Sounds like there's no need to tear into the monitor, at least. That is bizarre though. Try firing it up briefly with no fans or the bare minimum fans to keep it from cooking and see if that restores a flicker-less display. Disconnect the fans from the headers on the mobo (do you monitor fan RPMs? are they running in the proper direction and getting proper feedback?).

Have you added any new RF emitters around where your PC is? New cell phone/PDA/WiFi, etc. Put any new appliances in your living quarters that could possibly be on the same circuit? Any wiring changes in your building? Maybe take a multi-meter and check your outlets to make sure they have the right output, make sure that they are grounded properly, make sure that neutral and ground are properly bonded, etc. Check that your PC case is in common with ground. I'm kind of grasping at straws now :?:

If the fans were going to introduce enough noise to cause problems, I would have guessed you would have noticed it long ago.

No new RF sources. I'm clueless on anything requiring a meter. I think I have to try the mobo. Something must have popped.

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I am not an electrician but I assume that noise suppression is a normal configuration of all motherboards and I would guess that it is now faulty in yours. A new motherboard would/should fix the problem but so should the new cables.

I think I'm going to try a new mobo. Asus said they'd RMA it. At least they'd test/fix/replace and at worst stick me with a shipping bill.

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I think I'm going to try a new mobo. Asus said they'd RMA it. At least they'd test/fix/replace and at worst stick me with a shipping bill.

That's good. Keep us posted if you find anything out.

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