I tried various GeForce cards from 280 GTX and 9800x2, neither of which allowed bump mapping in Republic Commando. The 7900 class GeForce cards are the last cards to support bump mapping in Republic Commando. But, I found that the 7900 GX2 dual GPU cards I tried did not support old games like TIE Fighter, and go black screen when running Panzer General and old DOS games. So, after much trial and error before finally settling on the Radeon X1950 class cards that allow for both bump mapping in Republic Commando, and excellent support for older Windows and DOS games.
I am only scratching the surface here, but suffice to say, I have ordered hundreds of dollars worth of gear from eBay trying to find the perfect blend, and I think I have found it. I found that going beyond dual core CPU's caused from problems with DOSbox and other older games, perhaps those with real time clock limits, like Imperium Galactica 1. Now that I have found the sweet spot, I plan on buying four replacements for each individual component for when parts inevitably begin to die off. If at some point in the future PCs become powerful and versatile enough to run retro games in a virtual environment with custom hardware profiles, I will be able to retire my retro rig, but till then, I suggest getting the parts while you still can. In 10 years, finding 2005-era PC parts will be as hard as finding original Amiga 500 parts is today. I plan on being well situated to play Republic Commando for the next 20 years, if not more.
The LucasArts used modified distro of Unreal engine for this game.
Which used early version of gameworks by nvidia.
(nvidia made sure that this won't work on ati cards at the time, but this drm fired back at them with 8000 series cards because they started using same technologies that ati was using at the time, resulting in early gameworks not working anymore with their own cards)
So game makes calls to driver on card; Calls which do not exists in cards later than geforce 7000 series.
The Bumpmapping in this game never worked beyond low on dx11 AMD/ATI cards.
[it worked fine on x1950]
The only way to fix it, is through access to the source code of the game. Or developing emulator software that would translate gameworks calls in this game to today's standards dx api calls.
(I tried to fix this years ago, in 2006-2009, and no one was able to help me, your chance of getting this fixed in 2015 when lucasarts was acquired by Disney is below 0)
It's possible bumpmapping works on integrated intel graphics.