Flash your bios with the ATI bios that Dave posted here:
http://techpowerup.com/vgabios/61848/ATI.HD5870.1024.091112.html
You'll need ATI Flash and a bootable USB drive.
This is a pretty good tutorial on how to do the flash:
http://forums.overclockers.co.uk/showpost.php?p=15021144&postcount=1
Change the .bin file from this bios to a simple name, and a rom format. I named mine ati.rom
IMPORTANT ASUS INFO:
If you are using an Asus video card, they have locked their bios. You have an extra command to type in first to unlock the bios.
Perform in this order:
atiflash -s 0 backup.rom
atiflash -unlockrom 0
atiflash -f -p 0 ati.rom
I am using an ASUS 5870 right now, the Dell Bizlink DP-DVI adapter, and have been gaming in glorious eyefinity now for a week straight after unlocking the rom and flashing the bios and had zero, I repeat ZERO problems with the displayport monitor. Follow these steps and you too can prevent forest fire.
Edit: I misread the first post. Unfortunately this ATI bios doesn't maintain the overclocking and voltage tweak settings that have been found on MSI and ASUS cards, however, it does let you have eyefinity blink-free. Take your pick.