FPS slowdown (for me) is heat related.

Mac Technical Support
I posted a thread last week wondering if perhaps the slowdown some of us are seeing is heat related. At the time I wasn't very sure, as it was just a theory and I hadn't had much time to test it out. But now after the last week, I can say that in my case, it's 100% related to the heat of the GPU.

I have the 21" iMac 2011, with the AMD Radeon HD 6770M 512 MB. Long story short, while adding an SSD drive to the other internal SATA slot, I broke a pin off of the Optical drive fan, so it no longer works. After the upgrade (which was at the same time as the 1.03 patch, and 10.7.4) I noticed the exact same thing as lots of people are reporting. After a few minutes off playing, I would get the lag, slowdowns, etc. I also noticed that it was system wide, not just while playing D3, or WoW.

I did some experimenting, and downloaded a temp gauge. I noticed that every time my GPU heatsink hit 180 degrees, the slowdowns would occur. I assume it is just the GPU card protecting itself from overheating. As soon as the temps go back down under about 175, there's no lag or fps drop at all.

I downloaded this system preference : (note he has a specific one for laptops)

http://www.derman.com/iMac-Fan-Control

...and cranked up my other two fans to max to test. Temp on the GPU heatsink never goes over 170, and I have seen only little lags (just the normal ones when there is a ton of stuff on the screen) but nothing like the fps drops I saw before. I have been playing with this for a little over a week and can confirm this solved my issue.

Seems like the majority of people are seeing this in apple's laptops and iMacs, and it doesn't surprise me since those can get much hotter than the mac pros. Also in 10.7.4, Apple changed the SMC kernel extension, which among other things is wreaking havoc with lots of third party temp and fan control apps (like iStat Pro).

Not sure if it's D3 or Apple's latest update that is to blame, but for me, it's 100% heat related and the GPU cycling down when it gets too hot (which is my fault for killing my optical drive fan, which is the primary GPU fan as well). I would recommend anyone having this issue to try and ramp up their fans and see if this solves this issue. It's a work-around, and not an ideal situation, but it does work.
Also forgot to mention that I changed all of my settings back to the defaults, sound channels to 32, trillenear back on, etc.
WTF
are you joking?
d3 heat problem cause one of your fans is not working?
is that the conclusio?

there are not heat problems if your hardware works fine:

iMac mid 2011 27"
i7
6970m 2gb
12gb ram
43degrees overall
72 degrees gpu die
about 70 degrees gpu heatsink

playing maxed out

the games runs like !@#$ ... maxed out .. on lowest settings and so on and so on and so on...

forget d3
this game will never ever run on osx ... never ever
follow the sc2 tragedy ...

bb
Honestly, one of your fans is worst thing for a macbook pro. you need to fix that. you're going to bust out the existing fans trying to compensate and you still won't get the cooling you'd get with them all working.
It's an iMac. And that wasn't really the point of the thread to point out the ill advice of running a computer without the optimum fan cooling. It was to demonstrate what the cause of the fps lags could very well be.
This theory would hold true if you experienced similar slow-downs in other games. If you are not then it isn't heat related, it is coding related.
07/15/2012 04:30 PMPosted by Muckhammer
I also noticed that it was system wide, not just while playing D3, or WoW.
Thank you, thank you, thank you !!! It worked for me, exact same configuration and issue. Many thanks! ;-)

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