AMD Radeon Graphics - VESA Mode does not function

Using the nightly build from today (3a85677) i am unable to use VESA modes and ReactOS falls back to VGA mode.

GPU:  HD 6870

CPU: Intel Core 2 Quad Q6600

MBO: Asus P5N-E SLI

RAM: 1GB

Not really related, but installing the Radeon drivers works, but it causes as Assert to fail, j < 32. I am not currently able to provide logs, but i will be able to in a few hours.