We had an Early 2008 Mac Pro and decided to finally upgrade the video card. We found an ATI Radeon HD 5770 (Mac version) for a reasonable price. We needed to drive 3 screens from the card but hit some issues.
The Radeon HD 5770 has 3 ports – one DVI port and 2 mini display ports. I was able to drive 2 of the monitors without issue using the DVI port and a Mini DisplayPort to DVI cable. Attempting to use the third port resulted in no video on the third screen.
Googling found many articles about using 3 screens for the 2009, 2010 and mid 2012 Mac Pro models, but nothing official mentioned the early 2008 Mac Pro model. Even worse there were mixed opinions on whether it was possible to drive 3 screens at all.
Luckily the solution was pretty simple in this case.
You need to ensure the type of DVI to Mini DisplayPort adapters you are using are active adapters as passive adapters (which I had) will not work for 3 screens.
You will note that in most cases the active adapters cost quite a bit more then the passive ones. In this case I can confirm I bought some cheapies off eBay and these still worked without issue, allowing the Mac Pro to drive all 3 screens at native resolutions.
eBay auction for mentioned passive adapters
Apple Mini DisplayPort adapter FAQ
Mac Pro (Early 2009, 2010, Mid 2012) – Issues with three displays and multiple DVI, HDMI connections
Mac Pro (Early 2009, 2010, Mid 2012) – Supported display configurations
I started receiving the following errors every 10 seconds or so in my Console Logs:
27/03/10 4:59:21 AM com.apple.launchd.peruser.503 (com.akamai.client.plist) Bug: launchd_core_logic.c:4103 (23932):13
27/03/10 4:59:21 AM com.apple.launchd.peruser.503 (com.akamai.client.plist) posix_spawn(“/Applications/Akamai/loader.pl”, …): No such file or directory
27/03/10 4:59:21 AM com.apple.launchd.peruser.503 (com.akamai.client.plist) Exited with exit code: 1
27/03/10 4:59:21 AM com.apple.launchd.peruser.503 (com.akamai.client.plist) Throttling respawn: Will start in 10 seconds
After some googling I found several people experiencing the same issue. It appears this revolves around the use of the Akamai Download Client, which in my case was used when downloading an Adobe trial product.
The Akamai client was never uninstalled properly, either because I trashed the folder in /Applications/Akamai or because the uninstaller didn’t work correctly.
I did a spotlight search and found I still had a copy of the Akamai installer disk image – AkamaiDownloadManagerInstaller.dmg (If you don’t have this, go back to Adobe’s site and choose a new trial product to install, the Akamai client will then be reinstalled).
I reinstalled this and then ran the following from the terminal to uninstall the package correctly.
/Applications/Akamai/admintool uninstall -force
After running this, no more entries in my logs!