Mac Pro 5,1 + GTX 670 + ATI 5870 VRAM Usage

Redneck1089

macrumors 65816
Original poster
Jan 18, 2004
1,170
274
I have both the GTX 670 and ATI 5870 in my Mac Pro. Under iStat menus it only ever shows the 5870 (which is in PCI slot 1). It shows the card's VRAM as maxed out, for some reason.

Every once in awhile when I boot the computer it shows the GTX 670 and not even a quarter of its VRAM is being used. But 99% of the time it is the 5870 that is shown in the iStat menus.

I am not running any applications when it shows this. The system is completely idle.

Is this something I should worry about? Do you think it is just iStat menus messing up because of the dual GPU's, and with one being a Windows cards?


Thanks.
 

El Awesome

macrumors 6502
Jul 21, 2012
471
0
Zurich
How did you manage to check the usage of the GTX670? I have a 570 2.5GB and even while gaming iStat pro says 0% usage...
 

Redneck1089

macrumors 65816
Original poster
Jan 18, 2004
1,170
274
How did you manage to check the usage of the GTX670? I have a 570 2.5GB and even while gaming iStat pro says 0% usage...
I am using iStat 3. I have no idea how I am getting it to show the usage of the 670. It only shows the card every once in a while; most of the time (like I said, around 99% of the time) iStat just shows the 5870 with its memory usage maxed completely out.

It shows the 5870 in PCI slot 1 running at 58 degrees Celsius, but it doesn't show the GTX 670 at all.
 

Redneck1089

macrumors 65816
Original poster
Jan 18, 2004
1,170
274
I just unplugged the 5870 and left only the GTX 670 running.

iStat showed 0 usage.

The GTX 670 only has my main screen running on it - an Apple 30" monitor. Normally I keep both a Apple 27" monitor and a Wacom 12" cintiq running on the 5870.

I thought perhaps it was showing 100% usage because it had two monitors running off it, so after I reconnected the 5870 I took off one of the monitors. Alas, iStat was still showing 100% usage from the 5870.
 

The-Pro

macrumors 65816
Dec 2, 2010
1,449
37
Germany
istat menues 3 was never able to give me an accurate reading of VRAM usage.
If you are not on OSX 10.8 then you can use the application atmonitor to display VRAM usage and GPU usage. for 10.8 they had to disable all GPU monitoring function to make it work. Should be back soon according to the developers.
 
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