7970 Fan

[SamPotts]

So I've had a flashed 7970 (HIS) in my 4,1 Mac Pro and every so often it was displaying the random squares on screen (much like the Yosemite bug with iMacs). I thought I'd take a look at it to see if it was a heat issue. It only happened when waking from sleep so I assumed not but thought it best to check it out. I replaced the thermal pads as they were falling apart and also re-applied the thermal paste (with arctic silver). Now it seems to be raising and dropping the fan temperature every 10 seconds or so which is driving me crazy (it's not doing anything). The odd thing is, when I'm in bootcamp (windows 8.1), it's totally fine and behaves itself. Any ideas? I've tried PRAM and the SMC. I can't even monitor temps in OSX since it's a flashed card. Windows says it was 38-40c and fan was at 20% (minimum). OSX is going insane :/

 

[h9826790]

Is the PCIe fan or the 7970's fan? You can't fix the PCIe fan high speed by SMC / PRAM reset. In fact, it's doing the other way around. These reset may cause high PCIe fan on next boot. The easiest way to fix the PCIe fan issue is to stress the card for something like 30s. Luxmark can do it easily, it stress the card for 2min and automatically stop. Of course, you can use Furmark, or another software (even a flash webpage may do that job).

However, I will only do this if I confirm that my card's temperature is normal in Windows (not idle, but full load). Also, even with the stock Apple card, there is no temperature in OSX anyway. I have a Mac 4870, and a Mac 7950, both of them won't shows any temperature in OSX.

For the PCIe fan high speed error, AFAIK, one of the permanent fix is to put your card in PCIe slot 2. However, it means the slot 3 will be blocked. Not ideal if you need the slot for something else.

 

[SamPotts]

It's the fan on the 7970 itself rather than the expansion slots fan. I've got the 5770 back in for now because it was driving me mental, 5 seconds slow, 5 seconds sped up, 5 seconds slow... and so on. Doesn't do it on bootcamp windows which is even stranger, suggesting it must be Yosemite.

Do you think a graphics stress test in OSX would do "reset" it?

 

[h9826790]

I really don't know, this "stress reset" are for the known PCIe fan issue. Of course you can try it. However, since you just "fixed" the cooling system of you card. I will run more tests in Windows (and monitor ALL temperature parameters) before I stress it in OSX.

Also, if the other ROM is the PC BIOS (non EFI), you may switch it to the BIOS ROM and check if the same thing happen in OSX.