There's been a big deal made about UT3 Engine using Physx, so perhaps unsurprisingly, when you install Unreal Tournament 3 it also installs a PhysX engine.
I have been experiencing occasional temporary in-game lock-ups (~5-10 secs) in UT3 (only). It usually happens several times during a game which is very frustating, especially if one happens right at a critical moment.
I checked the Physx website to see if the Physx library had a later version in case that might be the cause of the lockups. Sure enough there is a later version available than the one that UT3 installs, so I uninstalled the old one and downloaded but didn't install the new one.
 
I rebooted then ran UT3 and guess what, UT3 still plays just fine without Physx being installed at all.  
 
This shouldn't be possible as its the physx engine that is meant to be doing the physics calcs (even if you don't have a physx card, it still is meant to be doing it, but in software so using the CPU) but I've uninstalled it and everything still works. Whats going on?
 
I'm guessing Ageia convinced Epic to include physx installer in UT3 just so they can claim UT3 uses it, even though it actually doesn't really benefit from it.
 
I fact I don't seem to get as many lockups since uninstalling physx so UT3 seems to work better without it. I'm a great believer in keeping my PC free of as much redundant resource-hogging sh[t as possible. It does seem that is exactly what the physx driver is, just redundant sh[t, at least if you're not one of those handful of people who actually bought a physx card.

uh.. there's a specific map pack for the Aegia card users, the physx card is only used in those maps.
 
I think this is the map pack
http://www.fileplanet.com/108145/0 [...] /Map_Packs
 
There is no difference with the default maps (the ones that came with the game).
 
All games that i've seen so far that have physx support, install a physx driver, it's quite annoying as I will probably not buy a physx card in the near future.

http://www.anandtech.com/video/showdoc.aspx?i=3171

OK I accept that UT3 might require the physx package if you have a physx card installed, but its certainly not appearing to use it otherwise.
UT3 still works (even maybe smoother) if you uninstall the physx package it installs by default.
Hopefully other UT3 owners will post here with their experiences after completely uninstalling physx.

the driver does nothing if you don't have a physx card
 
the card and driver does nothing if you're not playing the downloadable map-pack made for physx card owners.
 
the map pack for physx card owners can barely run on non physx card equipped pc's
 
suggest you go to epic's forums.. http://utforums.epicgames.com/forumdisplay.php?f=20
 
there are a few that have the aegia cards, I doubt anyone here has.

Hey Niz,
 
Like most games using Ageia PhysX cards, the game will run without it and therefore it is not a requirement to hold these cards. The install or drivers is there in case you own one of these and is used as a patch-driver most of the time.
 
However, with PhysX-brand games, PhysX card owners will benefits from greater physics/processing with the engines put in place in the game. GRAW uses a similar strategy where PhysX card owners will see more particles during explosions, etc.
 
You'll most likely see a hunge difference in particles flying everywhere if you use it with the Ageia Map Packs in this case.