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AMD 7950 performance degradation 3,1 -> 5,1

fuchsdh

fuchsdh

macrumors 68020
Original poster
Jun 19, 2014
2,039
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So I just swapped the Radeon 7950 I had sitting in my 3,1 to the new 5,1 I got. Running Valley benchmarks, however, I'm seeing a dramatic drop in performance. On my 3,1 I got scores of ~1230/29.5 average FPS. And now I'm getting 830/19.8 on the same Extreme HD preset, which is basically what I got with my 5770 in the 3,1. No temps seem to be out of whack, so I'm wondering what the possible issue could be.
 
have u updated drivers of 7950?

that drop in performance makes no sense whatsoever.
 
msbc said:
I have the 7950 in a MP5,1, 10.9.4. I'd be happy to provide a comparison benchmark if you detail the one your running.

Mark
Click to expand...

Extreme HD preset (no changes made to the option.)

Ran it again.

9GO6Hrv.png


Just checked Sapphire's site, they say no reason to use the driver if you're 10.8.3+

The only "off" part of my config at present is that I'm running just 4GB of RAM while I await a 24GB 1333 kit. But I wasn't aware the Valley benchmarks were influenced by RAM, heavily or at all.
 
Did you try reseat the card, or SMC reset etc?

Is there anything strange thing the system profile?

How about other benchmark software? All running low?
 
try

sudo rm -rf /System/Library/Extensions/AppleIntelCPUPowerManagement.kext
sudo touch /System/Library/Extensions


helps to prevent 7950 being slow in 10.9+ on MP3,1. Might help you as well.

There is no known regressions caused by this hack.
 
Did an SMC reset, reseated the card, double-checked the 6pin connectors, and ran the terminal command + did a restart. It got better... not any better than my 3,1, though.

yi68JUU.png


The fans are also spinning up audibly on the 5,1 where they never did on the 3,1--getting to 1900RPM on the PCIe slots and 1400 on the PSU. Do I just need to smcFan to stop it from doing that?
 
fuchsdh said:
The fans are also spinning up audibly on the 5,1 where they never did on the 3,1--getting to 1900RPM on the PCIe slots and 1400 on the PSU. Do I just need to smcFan to stop it from doing that?
Click to expand...

same here. unfortunately this is perfectly normal behavior. my 3,1 was much more quiet than 4,1/5,1 when the GPU is used heavily.
 
If the fan speed stay there (not under heavy load), you can use SMCFanControl to set the PCIe fan to max, and then turn it back to auto straight away. The fan should slowly spin down and back to it's normal speed (it takes few minutes to spin down). The idle speed should be 800RPM even though with the HD7950 installed.
 
mikeboss said:
same here. unfortunately this is perfectly normal behavior. my 3,1 was much more quiet than 4,1/5,1 when the GPU is used heavily.
Click to expand...

Well drat. I noticed that it was a bit louder in general, as well. Let it not be said then that the 3,1 has its merits! :)

h9826790 said:
If the fan speed stay there (not under heavy load), you can use SMCFanControl to set the PCIe fan to max, and then turn it back to auto straight away. The fan should slowly spin down and back to it's normal speed (it takes few minutes to spin down). The idle speed should be 800RPM even though with the HD7950 installed.
Click to expand...

I'll try that when I get home. Thanks.
 
Well I don’t think the issue is the actual Radeon’s fan, it’s the PCI fan on the MP. So if both let me throttle that, I will try it :)
 
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