To add to the info above, you have D2S HID bulbs for low beams that are also your bi-xenon high beams.

A lot of people here get the more powerful Osram Nightbreakers from Powerbulbs, they have the best price IMO on proven legit not fake Nightbreakers

In this case I dont think the bulbs are the problem though.

I suggest following the troubleshooting suggestion above to swap parts side to side and hopefully narrow down the malfunctioning component. Quite a few parts could be causing that problem.

__________________
04 X5 3.0i auto
03 X5 4.6is