4870 issues.

[BlacklinePC]

Hello Mac forum members. I have a Mac Pro 3.1 running Snow Leopard. Im having issues with the 4870 I flashed to work with it. The Mac will boot all the way up until before the logon screen. Then it will give me a black screen and not do anything. The device manager sees both cards (2600xt and 4870) if I plug the DVI cable into the 2600XT. I used this guide to flash it
http://web.me.com/jacobcroft/4870Flash/4870Flash.html

and I used the Rom from this thread
https://forums.macrumors.com/threads/668710/

This is the card I bought
http://cgi.ebay.com/ws/eBayISAPI.dl...236995&ssPageName=STRK:MEWNX:IT#ht_500wt_1182

any help?