Now dust has settles a little what video card should I upgrade to

[Rick Lang]

Mitch, you made the right choice at the time. Although the ATI HD 2600 XT (used in the 2008 Mac Pro) and ATI HD 2600 PRO (used in the 2008 iMacs) cards support the minimum VRAM requirements, they do not support OpenCL.

https://support.apple.com/kb/HT4664

Rick Lang

iMac 27” 2.8GHz i7 16GB

[Craig Seeman]

Apple has an inexpensive miniDisplay to DVI adaptor. $29.

[Daniel Wilson]

One of the Barefeats pages which Craig pointed out talks about successfully running three monitors off the 5770 and 5870, on Mac Pro’s from 2006 to 2010, so I think you’ll be alright with two monitors. It also talks about which adaptors you’ll need.

It’s this page, about three quarters of the way down:

https://www.barefeats.com/wst10g6.html

Cheers,
Dan

[Lydia Robertson]

I am particularly curious about the 6870 card’s HDMI port. Do you find it is working well?