What version of mac os X are you running?
Snow leopard 10.6.4
Do you have anything plugged into the mini display ports?
The first time I plugged the card I only used the DVI port then I bought a mini display port to DVI adaptor and a mini display port to HDMI adaptor so I could try it on my TV.
Now did you remove the graphics card you had before?
Timeline: I first took out the old card and put in the new one as per instructions. I connected my display ( a 22" viewsonic) with the DVI cable I've always used with the x1900 card through the DVI output of the new card. I had no mini display adaptor so it was my only option at that time. I then rebooted and the Apple logo appeared with the silver-white background and a spinning wheel as the computer was booting up. As soon as the hard drive stopped making noise (computer finished booting) the display went dark with a "no signal" sign. I rebooted a few times with the same result. My next step was to take the new card out and put the old card back and go on the net to see if I missed anything. I then installed the new card in slot 1 and the old card in slot 3 (the card is double slot) and plugged my display in the old card.When I rebooted a pci utility came on to ask me about lane width choosing: ATI Radeon 5770 is at 16x and ATI x1900 is running at X1. I didn't try out any other setting because my x1900 was working fine. I then opened up System Profiler and from there could see both cards . I retried to plug the display into the new card with no success so the next day I went out and bought the adaptors and retried everything with no success.
Ok, thank you for the information. Try downloading and installing the 10.6.4 system update again. You will want to install the full version. You can get it from the following web site http://support.apple.com/kb/DL1048 After you install this reboot and make sure the old card is still working. Then power the system down. Then connect the display to the new cards dvi.
let me know if that works.
It seems to have done (half) the trick! I did re-install the 10.6.4 pack and finally got the mini display ports to work but only thru my TV with the mini display to HDMI adaptor. I still can't get anything out to the Viewsonic 22" display but I now suspect the cable. The 5770 has a dual link DVI output and the display has a DVI input but the cable between them is a Single link DVI. Can that be it? I'll get another cable tomorrow and try it out . Thanks. I'm lot closer than I was yesterday.
If you can tell me if I'm wasting my time with changing the cable to a Dual link one I'll look for something else. In any case I'll accept the answer. thx again
Glad to hear we are moving forward. I do have one note. If you used the mini-display ports on the 5770 you will not be able to use the DVI port as well. From what I was reading it's something about the card that doesn't let you. You would need to pick up the mini display port to dvi to have the monitor running on that card as well.
Thanks I'll try that.