Fan Control Speed Update Interval

SickBoy254698

What impact if any will lowering the update interval have? (I'm not asking what it does I'm just wondering if a lower interval would have any adverse affects.)

Also what do you recommend the update interval be set too? It defaults to 5 seconds but most other programs default to 1 second so I was just curious.

Lastly, thanks for finally enabling the GUI fan speed feature. I know it was done before but in GPU Tool it didn't work properly. You have no idea how happy I am that I no longer have to go through the ordeal of setting up custom fan control with Riva Tuner. What used to take 5 minutes every time I changed drivers now will take all of 15 seconds. I don't want to sound like a queer or nothing but if you were here right now I would kiss you.

Unwinder · 10-09-2009, 09:06 | posts: 10,318 | Location: Taganrog, Russia

Quote:

Originally Posted by SickBoy254698

What impact if any will lowering the update interval have? (I'm not asking what it does I'm just wondering if a lower interval would have any adverse affects.)

Sending new fan speed to fan controller is not a fast process. And depending on system configuration and fan controller type this process can be really CPU performance consuming (for example, on NV 9600GT and AMD 48xxx series fan controller resides directly in GPU so the access to it is rather fast, whilst on GTX 200 series the controlelr resides in external dedicated chip so passing data to it throught GPU eats more time). And if you're on multi-GPU system, CPU performance hit will increase by factor equal to number of GPUs in the system, because each GPU fan controlelr will be re-programmed on each period. So it is strongly recommended to leave it at default value (one fan speed update per 5 seconds) and to decrease it carefully with understanding of the facts expalined above and monitoring system performance when decreasing update period.

SickBoy254698 · 10-10-2009, 21:58 | posts: 658 | Location: Someplace very, very hot.

Thank you sir!

Initialised · *Last edited by Initialised; 10-20-2009 at 23:35.*

Any delay between reading temperature and applying fan adjustment could lead to oscillation. The gpu heats up, the fan speeds up the gpu cools the fan slows. If you have a noisy card then this can be more annoying than a steady fan drone. To avoid this I used Furmark to find the temperature where this starts happening and lower or flatten the rate of change. So an excessive delay could lead to thermal spikes, and as Unwinder said frequent measurements could hamper performance on some systems.

For empiricisms sake: Furmark 1.7, 4870x2 @ 790/1100, 1600x1200-8xAA-Post Processing-Xtreme Burning Mode 60s per test.

Fan int vs FPS
100______26
200______26
300______27
400______28
500______29
1000_____29
2000_____30
5000_____30
10000____30
20000____30

Afterburner off: 33

So there is a significant impact on performance below 2000ms so the recommendation on 5s is reasonable. With AB turned off I gain 3FPS, that's a 10% hit on the flip side having my system run much quieter at idle is definitely worth the hit.

Unwinder · 10-21-2009, 07:05 | posts: 10,318 | Location: Taganrog, Russia

Quote:

Originally Posted by Initialised

Any delay between reading temperature and applying fan adjustment could lead to oscillation.

There is no delay if you increase fan speed update interval. If you set it to 5 seconds for example, Afterburner is just reading temperatures with the same interval too, recalculates fan speed according to it and applies it immediately on each period.

Quote:

Originally Posted by Initialised

So there is a significant impact on performance below 2000ms so the recommendation on 5s is reasonable. With AB turned off I gain 3FPS, that's a 10% hit on the flip side having my system run much quieter at idle is definitely worth the hit.

Set ShowPerformanceProfilerStatus = 1 in MSIAfterburner.cfg to display the profiler. I bet that major performance consumer is actually hardware monitor in this case, rather than automatic fan speed control.

Initialised · 10-21-2009, 22:50 | posts: 32 | Location: Newcastle upon Tyne

Quote:

Originally Posted by Unwinder

There is no delay if you increase fan speed update interval. If you set it to 5 seconds for example, Afterburner is just reading temperatures with the same interval too, recalculates fan speed according to it and applies it immediately on each period.

Not exactly what I meant, the longer there is between adjustments in fan speed the larger that adjustment is likely to be due to a larger change in temperature between polling intervals and therefore a more noticeable change in fan tone, the system is under-damped resulting in oscillation. You can see the effect happening as a jagged/zig-zag in the rising section of the temperature vs time curve when load is applied. I guess it is hard to achieve critical damping with limitted data (steps of 1% and 1C) without making it more resource hungry.

Quote:

Set ShowPerformanceProfilerStatus = 1 in MSIAfterburner.cfg to display the profiler. I bet that major performance consumer is actually hardware monitor in this case, rather than automatic fan speed control.

I've noticed a performance hit with GPU-Z too. Can the fan profile work with hardware monitoring turned off?

Initialised · 10-21-2009, 23:08 | posts: 32 | Location: Newcastle upon Tyne

OK, just answered that one! With all the monitoring off the fan profile didn't kick in properly and there was no change in performance.

SickBoy254698 · 10-22-2009, 01:00 | posts: 658 | Location: Someplace very, very hot.

If you're monitoring everything and using the custom fan profile the program only requires CPU time for a spilit second every 1-3 seconds. The impact on performance is going to depend on what type of CPU you have and what programs you are running at the same time.

I live in Phoenix, AZ and the high temperature in summer averages 41C/107F so I tend to monitor temps frequently and go overboard a little. When I do I run Afterburner, Everest (monitors 6 other temps) and Fraps since I usually only run everything when I'm gaming. With all that going I've never noticed a performance impact of any kind that can be directly attributed to the monitoring programs I'm running.

EdKiefer · 11-06-2009, 16:20 | posts: 78

Do you have to have AB running all time for fan control or can it be setup to startup, an be able to be closed and still control fan speeds ?

Unwinder · 11-07-2009, 09:53 | posts: 10,318 | Location: Taganrog, Russia

Quote:

Originally Posted by EdKiefer

Do you have to have AB running all time for fan control or can it be setup to startup, an be able to be closed and still control fan speeds ?

If you're talking about software automatic fan speed curve then yes, of course AB must reside in memory to perform fan speed automation.