Problem using 2 Graphics Cards in Mac Pro 2012

I hope someone out there has encountered this and has a solution. I have a mid-2012 Mac Pro with 12 cores and running 10.10.4. I have 3 monitors and originally had them all connected to the 3 outputs of the ATI Radeon HD 5770 card that came with the computer. I also have an older Mac Pro (2007) which I no longer use. It had a nVidia 8800GT graphics card that worked perfectly. So, I thought that I could improve the performance of my main display (30" Cinema Display) by not sharing the 5770's resources among 3 monitors. So, I installed the 8800GT and connected the other 2 monitors to it. Here's the problem:

I have to startup the computer with the monitors unplugged from the 8800GT. Then, I can plug them in and they will work perfectly. If I put the computer to sleep, and then wake it, all is OK - all 3 monitors are working. However, if I do a shutdown, and then restart, only the 30" monitor connected to the 5770 turns on. I then have to unplug the other 2 monitors from the 8800GT and plug them back in and then they will work. Even if I power the monitors connected to the 8800GT off, and then turn them on after logging in, they don't work - they have to be physically disconnected and then re-connected. Needless to say, this is a pain - especially since the computer is buried under a desk.

When I look at System Resources, and select "Graphics/Displays", I see both graphics cards listed - even when the monitors connected to the 8800GT are not working. If I select "Displays" from System Preferences, all 3 monitors will be shown - even if the 2 connected to the 8800GT are not working.

Posted on Sep 7, 2015 11:34 AM

18 replies

Binone Author

Level 1

1 points

Sep 8, 2015 12:03 PM in response to The hatter

Thank you. I'm thinking that the best approach may be the one you suggested. At some point, I'll get a more powerful graphics card than the 5770. For now, I've removed the old Geoforce 8800GT - it was producing a huge amount of heat and I really didn't see a benefit from adding it. I've got 2 monitors connect to the 5770 and 1 via a DisplayLink adapter. That seems to be working well. The 2nd monitor on the 5770 is only used for email, so hopefully, the majority of the 5770's resources go to the 30" Cinema Display. Time will tell. But for now, it's stable and working well. For photo editing, it seems OK - some effects take 2-3 secs to render, but if that's a problem, then I'm just getting too impatient. I've got some video editing to do and if I notice a big slowdown when I do that, I'll have to bite the bullet and buy a more powerful card. Thanks again.

The hatter

Level 9

61,031 points

Sep 8, 2015 12:32 PM in response to Binone

FCP-X is one app that now is designed to make use of 2nd (3rd etc also) but not usually.

Adobe prefers GTX from Nvidia.

Both can benefit from GPUs with more VRAM - photoshop has for years needed 2.5GB VRAM or above.

Putting the system on - in order of preference - SSD / SATA II / SATA III PCIe controller / PCIe bridge adapter - going from 250MB/sec to 500 to 1300MB/sec. Also handy for Lightroom or scratch to be using SSDs to reduce slow writes and reads and when large size and amount of files being shuffled into and out of memory/processor.

And having 'enough' memory for apps, data, and cached data (virtual memory volumes aka "RAM disk" of olde).

Lots of tips to look through: http://www.macperformanceguide.com

A 5,1 is also easy enough to upgrade processor if you want one or two 6-core 3.4GHz units, which have gotten affordably cheap.

Binone Author

Level 1

1 points

Sep 8, 2015 1:08 PM in response to The hatter

I'm going to look into a GTX card - the majority of my graphics intensive apps are from Adobe. My system currently has:

32G Ram

2 6-core processors at 2.4G

2 SSDs (both are SATA). 1 is the Boot & program drive and the other the Adobe Scratch Drive

3 Multi-TB HD drives for data, photos, etc.

I've seen some reports that minimize the gain achieved from having 12 cores, vs 6 or 4 and also increasing processor speed. One app I use extensively is DXO Optics Pro - it does my RAW conversion and lens distortion correction. On a 12 core machine, it processes 12 files in parallel, so I definitely get a boost from that and I suspect it would even be faster if the processors were 3.4G, but as it stands now, it runs pretty fast so gains may be minimal. It's possible that the biggest gain would come from a better graphics card and, possibly, a PCIe SSD boot drive.

I'm going to try to find an article about the process for upgrading the processors to 3.4G. As long as that doesn't involve over-clocking, and isn't too expensive, it may be a worthwhile upgrade.

Thanks again.

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Problem using 2 Graphics Cards in Mac Pro 2012