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Old 03-13-2013
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Question Electrician's Thoughts on this?

I need some insight from people more knowledgeable regarding house circuits!

For some reason, after I began using the latest EVGA GPU artifact scanner the ceiling lights (CFL's) in the room will faintly pulse once a second every second, in a perfectly steady fashion.

Keep in mind I've built rigs that could draw almost 900w from the wall and never seen this during stress testing. Other programs that load down the system don't do this at all, it is specific to this one program. The current system in question should be well under 500W, it's a single stock GTX 480.

Was in the middle of replacing a UPS so the computer is plugged directly into the wall. The remaining UPS reports the wall circuit voltage only changes from 119v to 118v when I start the GPU test.

It doesn't look at all like a load problem given the circuit voltages remain high and I know there's little else running on this one circuit at the moment. Could the PSU be putting some kind of noise back into the circuit, and if so I would presume it means there's a room/circuit grounding issue?
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Old 03-13-2013
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Yeah, you have a "ground leak" somewhere. Since the PSU's EMI filter (and the UPS' as well) shunt noise to ground, the CFL's inverter picks up a specific (anti-)resonant frequency that makes a dip in the voltage output. You could probably stuff a capacitor somewhere along the line between the PC and the CFL, but that's only fixing the symptom, not the cause. Can't tell you anything about fixing your ground line without actually being there...
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Old 03-13-2013
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Do any other stresses make it happen? Furmark (which is what evga's thing and msi's thing are based off) is actively throttled by GTX480 and newer. It's possible you're seeing an artifact of that.
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Old 03-13-2013
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Thank you McSteel. Was what I was assuming but I'm glad to have more knowledgeable opinions on it.

No other stresses make it happen. I run F@H 24/7 and that doesn't do it either. EVGA recently added a combination furry-tessy stress test image to their OC Scanner X program and that seems to have the most pronounced flicker of the three images. The GPU load indicator will flick between 93% and 99% similarly with the lights, about once a second.
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Old 03-13-2013
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Okay... Bobnova may be right about the throttling thing. This is weird.

I've installed the other UPS... plugged the computer into it and it into a different socket. I'm still able to make the lights flicker on demand. But what is strange is that the system load (455w with CPU+GPU folding) when I use the artifact scanning test causes the UPS load to go nuts. It literally bounces between readings in the mid 300s, 400s, & 500s, with a spike to ~830w and a dip to 230w repeatedly thrown in for good measure. I've never seen such erratic load readings before...
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Old 03-13-2013
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GTX480s woefully violate PCIe spec when faced with furmark if they don't throttle, so Nvidia implemented a half hardware half drivers throttling setup for them. It doesn't work overly well, but it keeps them and their MOSFETs alive and keeps the card somewhere vaguely close to PCIe spec, sort of.
The 580s have hardware+firmware+drivers and do a better job of it. The 680s have hardware+firmware and do it very well.

Mostly, Furmark and it's related fuzzy-whatever things aren't actually a good stress test anymore because all the drivers do their best to throttle them.

I wouldn't worry about it, though I would recommend against continued running of Furmark.
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Old 03-14-2013
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I'm not actually using Furmark, I'm using EVGA's OC Scanner X program. If anyone remembers that ATI Tool program of old, it was the first load tester that could scan for and detect artifacts, including those invisible to the eye from unstable GPUs.

OC Scanner X is an actively developed modern equivalent program by EVGA that just happens to borrow furmark code. I don't use it for load testing per se, simply artifact scanning. And the load is still pretty strong even with the load throttling, as the power consumption exceeds 500w even with the CPU idle. (Again, F@H fully loading the CPU+GPU averages a steady 455w by comparison)

I just can't believe how erratic the throttling appears to be, that's some pretty extreme fluctuations. The card is fully watercooled so even with OC Scanner running it stays in the low 60's, despite the absurd power draw. EVGA's Scanner has optional settings to limit loads on 500 & 600 series cards, but not for the 400's.
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Old 03-15-2013
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That's furmark. Anything with a fuzzy shape is a furmark wrapper, EVGA added an attempt at artifact scanning (software artifact scanners aren't that great either, they cannot see the screen after all). As with anything involving furmark, it's capped like I said.

You can't disable the load limit on a 600 card. You can partially do it in drivers on a 500.
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