Sapphire Radeon HD 7950 Mac Edition; how is it?

[MacsRgr8]

So, I got the Mac Edition of the 7950 in a Mac Pro 2008.

In OS X Mountain Lion, the screen flikkers occasionally.
In OS X Mavericks, the screen-flikkering is over.

BUT: In OS X Mavericks the card performs much worse than in OS X Mountain Lion.
I used the Unigine Benchmark apps (Heaven and Valley).

Netkas confirms this...

 

[crjackson2134]

So did you try the workaround for this? Just wondering if that took care of your problem. I too am wondering if this only applies to the MP 3.1 . Would I have have this problem on my 5.1 also?

 

[MacVidCards]

So, I got the Mac Edition of the 7950 in a Mac Pro 2008.

In OS X Mountain Lion, the screen flikkers occasionally.
In OS X Mavericks, the screen-flikkering is over.

BUT: In OS X Mavericks the card performs much worse than in OS X Mountain Lion.
I used the Unigine Benchmark apps (Heaven and Valley).

Netkas confirms this...

Netkas found the fix. Remove the AppleIntelCPU power management kext.

Works in my 3,1

 

[h9826790]

The 7950's performance in my 4,1 has no problem at all, so it seems this only the 3,1's problem.

 

[MacsRgr8]

Netkas found the fix. Remove the AppleIntelCPU power management kext.

Works in my 3,1

I read that too, but is that a real fix?
It seems that you disable some Power Management features, which might have some negative effects on the long(er) run..?

EDIT:
Just did an experiment on the named Mac Pro (3,1 with Radeon 7950):
Added a partition and installed Yosemite DP 7 on that partition.

Yosemite has the same "issue" as Mavericks:
Far worse 3D performance on the 7950. In the above mentioned benchmark apps (Heaven and Valley by Unigine), the performance is about 50% - 75% of running the same app on OS X Mountain Lion.

Then I removed the two .kexts (AppleIntelCPUPowerManagement.kext and AppleIntelCPUPowerManagementClient.kext) as mention by Netkas in Yosemite, and the performance was up to par with Mountain Lion.

In Mountain Lion those two .kexts are also in place...

Judging by their names, it must do something with Power Management (duh..), but Netkas mentions that it seems not be a real issue to remove them:

...speedstepping still works, cpu isn’t hot/cosuming a lot, still drops the clocks.

So, my question to:
• Is there really no issue with Power Management like Netkas said, or might there be some other issue when removing these?
• Do those two .kexts simply do nothing when unsupported hardware (i.e. the Mac Pro 3,1 with the Radeon 7950) is found?