Problem with test release v1.01 noise in power supply!!!

[abstrax]

Thanks for reporting the issue. We didn't experience the problem, but our office is not very silent either and I guess it occurs only on single GPU setups. We mainly use dual-GPU setups...

I'm not sure what is happening, but my guess is the following: The post-processing is run on the GPU of course, but it's a whole bunch of smaller kernel calls of constant complexity and execution time, which make the GPU alternate between 100% usage and idle very quickle, roughly in the frequency range you can hear. As a consequence, the power supply has to alternate the provided power accordingly, which means alternating high/low currents on the PSU. This may cause some expansion/contraction on some parts (capacitors for example, but I really don't know), which you can eventually hear.

If you use multiple GPUs they don't run synchronously, which means that the post-processing doesn't overlap exactly, which may reduce the strength of the power cycle.

Is it dangerous to the hardware? I don't know. Can we do something about it? I think so, but I don't know for sure.

Cheers,
Marcus

[pixelrush]

I would think this is very undesireable behaviour for circuits.
The PSU ought to be handling load changes some seconds or minutes apart and keeping everything ripple free. Having cycles of full load to zero in milliseconds is not what its designed to do unless its a PWM supply and more than likely leads to surges and spiking and other transient noise in the lines which would upset the regulation of the mobo etc. More than likely too the PSU fans are getting signals to run full or slow very rapidly - depends how it is designed. Probably the various ICs and gpu don't like this treatment either. I suspect it wouldn't be good for longevity.
I think this definitely should be changed and actually until you sort out a solution or verify the nature of the problem you should probably take down the zips and advise people not to use it.

[abstrax]

I don't think it's that bad. We didn't hear anything of that kind and I'm really surprised that these types of issues are actually possible. We have to investigate it and we will try to fix it, but if you are worried about your hardware, then don't use the post processing tools.

Cheers,
Marcus

[abstrax]

Some more questions: Does the sound change, when you change the screen resolution? For example, does it have a lower frequency if you render larger images and higher a higher frequency, when the images become smaller? What happens when you change the number of glare rays?

Cheers,
Marcus

[Slide3D]

Some more questions: Does the sound change, when you change the screen resolution? For example, does it have a lower frequency if you render larger images and higher a higher frequency, when the images become smaller?

yes. for biggest res duration signal noise increases and are becoming quieter

What happens when you change the number of glare rays?

it works like a volume setting
the more light the louder noise

[franbec]

I have this weird noise too, ( 600 w psu(cheap), and a single gtx 560ti), but imho , do not think it will be harmful for the psu, modern psu´s bring all kind of protections, must be an strange coincidence in the frequency of the gpu power demand, that can makes flow a current at a frequency of approx 600 Hz., probably by the toroidal power inductors chokes, producing a loudspeaker effect by the small vibration of that inductors at that frequency, imo, without further consequences, or effect in the ripple of dc supply. Tomorrow i will observe the DC lines with an oscilloscope. with the effect working. i think this effect is more a problem of a not high grade psu, (like is my case), check how much did cost your psu,( that do not means the psu is not working ok, or not protected, only that not use top quality components) check with a better quality psu, if the Mog synthesizer effect continues. it is only my opinion, but I can be wrong.

[Slide3D]

Post processing uses GPU, not CPU.
Otherwise it would not be interactive.

http://render.otoy.com/forum/viewtopic.php?f=39&t=26043

[Slide3D]

my PSU:
FPC Everest 80Plus 800W
bought 4 months ago

[grimm]

Excellent, lots of cool stuff to play with.

When I first started Octane an error message popped up:

Code: Select all

Error

Could not store offline data. Please make sure that there is enough space on the application drive.

I have 276Gbytes free on that drive so I'm not sure what it is complaining about? It doesn't appear to effect how the app is running. I didn't get the error when I restarted Octane.

I have two video cards so I don't hear the noise when I enable post processing.

Jason

[abstrax]

Excellent, lots of cool stuff to play with.

When I first started Octane an error message popped up:

Code: Select all

Error

Could not store offline data. Please make sure that there is enough space on the application drive.

I have 276Gbytes free on that drive so I'm not sure what it is complaining about? It doesn't appear to effect how the app is running. I didn't get the error when I restarted Octane.

I have two video cards so I don't hear the noise when I enable post processing.

Jason

Is it possible that you accidentally opened Octane 2x at the same time? If yes, both instances tried to write the offline data at the same time, which causes one instance to fail and this message pops up.

Cheers,
Marcus