To clarify usage: I mainly need it for large spreadsheet files and stock trading. I do not do much gaming. Budget is not a problem - I just want plenty of GPU power to drive the beautiful U2410s at 1920x1200 each. Thanks again
two 5850s would do the job but might be overkill. I assume your not gaming right? (other wise 3 is better than 4)
Are you video editing or doing any other graphics intensive job?
if not, you could get away with two 5670s. They cost $70 a piece and should do very well for a 4 screen cf setup.
Make sure you have an extra pcix16 slot on your mobo though (it can be running at any speed, just x16 form factor).
For your 5850, you can buy a new fan on ebay for $15. It won't do 4 displays though. And you might have trouble finding another 5850 in stores, they seem to be discontinued... ebay has them for ~$150. Actually $150 + $15 for a new fan might be something to consider seriously. Two 5850s would provide quite a kick and even handle games with lowered settings if you decide to use 3 of the displays for the occasional game.
ok pretend my first reply was before your second post.
I just realized something like the 5870 might be more suitable to your situation. They come with 6 display ports and actually support 6 monitors. Not sure if there are newer equivalents, someone else know? There is also the firepro series made for workstations. My advice is fickle in this area though, so i'll let someone else respond.
edit: mixing cards causes problems. Some cards "can" be mixed but it isn't recommended.
Thanks for all your help! I notice these 5870 and 6950 cards allow multiple displays using Displayport 1.2. Silly question, but does that mean I can somehow use one cable to connect 2 monitors, then the HDMI and DVI for the other 2 monitors?
Will I need to buy some adaptors? I know the U2410 accepts displayport, but no idea if this means that the 1.2 version will work on it. Sorry for all the newbie questions!
Also, you can run 2 monitors off of a single card with no issues but for monitors 3,4,5, or more you will need an active dongle for each one. As an example, the 6770 has two dvi ports so you can connect your existing two monitors up with no problem but if you plug monitor number 3 into the hdmi or mini display ports it will not power up unless you use an active adapter. I would suggest using the two dvi ports on that card and then getting two mini display port to whatever connection you want to use on the monitors but make sure they are active adapters or they will not work.