2008/2009 Mac Pro 8 core Video Card questions

User Tip: Mac Pro silver tower (2006-2012) Replacement Graphics cards

http://forums.macrumors.com/showthread.php?t=1440150

Can you post the reports/logs that say the 2009 has video issues?

2009 is crashing with a video issue listed on the crash reports.

Note there are problem with 10.11 when you have to or more video cards and have monitors connected to more than one card.

Mac Pro keeps logging out since El Capitan

http://forums.macrumors.com/threads/mac-pro-3-1-with-nvidia-gt610.1819488/

Will mavericks support a gt 610 1gb

http://forums.macrumors.com/threads/geforce-gt-610-on-macpro-2-1.1753187/

Same issue on my 2008 Dual Quad Core. Had 3 monitors. Screens were becoming scrambled. This occurred after 2 days on el capitan. Unplugged all but one monitor. Then used F3 and found that system had 27 screens saved! Deleted all but one, then re-added a screen for each app using just one monitor. This has fixed the issue with screen scrambling. Appears that el capitan is getting into some sort of screen loop and with the older processors is overloading the video cards or bus so that garbage is displayed. Unloading the card and video bus by physically shutting down the extra monitors has solved the issue. I will see if I can add back one or two monitors on another card to get some of my real estate back. I have two video cards, so will try one monitor with each card and see if that works. The cards are capable of 2 monitors each. Puzzle is that on initial install, this was not an issue. System has constructed or indexed a video memory that created the problem. This could be a leakage issue since I definitely did not have 27 screens on my F3 before this install unless Yosemite was doing bad things in the background.

My Early 2008 dual quad core i7 is running ONE NVIDIA GeForce GT 120 1024 MB graphics fine with 2 monitors.

The other NVIDIA GeForce GT 120 1024 MB graphics in another slot is not working now. Was working with Yosemite. So I've lost dual card and the ability to have 4 monitors with el capitan with these GT 120 video cards. Have no idea why one will work but the other will not. The cards have some external differences but show as the same in the finder. ROM revision in the working card reads "preset 1.0.0". The non-working Card ROM reads "3386".

Working card has VGA, HDMI, and DVI. Non working has dual DVI and RGB, so may be an older chip set.

Official support lists these as compatible: About graphics-card compatibility between Mac Pro models - Apple Support

Graphics cards for Mac Pro (Early 2008)

• ATI Radeon HD 2600 XT
• NVIDIA GeForce 8800 GT (part number 630-9191 or 630-9897)
• NVIDIA Quadro FX 5600
• ATI Radeon HD 4870, offered as an upgrade kit
  Note: The Radeon HD 4870 card requires Mac OS X v10.5.7 or later.

Presently there is a problem in EC that prevent running monitors on two cards in a silver tower Nac Pro

Mac Pro keeps logging out since El Capitan | Apple Support Communities