Hello. I just bought a Galaxy KFA2 9600GT OC along with a OCZ StealthXStream 600w (not sure on the exact name of processor).
 
Specs:  
Windows XP
HP Presario SR5152NX
AMD Athlon X2 4000+
2GB DDR2 PC-5300 Ram
250GB HDD
OCZ 600W PSU
 
I run Oblivion... decently..at 1680 x 1050. Doesn't matter what resolution it's at, it's pretty much the same. Through tunnels and such, it's like 100fps + (not even sure why, my friend said its locked at 60, but its like this  even with VSync on I think). The first fight scene when the guards fight the red robed people in the beginning, it drops to 16 being lowest, and 26 being highest FPS. Even outside it's only decent.. 30-40 FPS. No idea why this is.
 
Installed latest drivers, tried deleting old drivers completely and installing the 175 version.. still nothing. I turned settings down and turned off stuff, and even put the resolution on 1152 x ___, and still same FPS. Nothing is edited in the nVidia control panel.. all is application controlled.
 
My friend has the exact same setup except he has a 5000+ and Vista. I seriously don't think that would make a drastic change. Except.. he gets 60+ fps on that exact fight. He has an HP computer as well. Not mine exactly though.
 
What's going on.. I was excited to upgrade from integrated but this card is performing mediocre at best.

oblivion takes it's toll on the whole system not just gpu.
 
when dealing with npc's you may be running into trouble with your cpu although i wouldn't have thought so.  
 
What are you referencing that makes you think you should get more fps?

My friend only has a 5000+ and he gets a solid 60 FPS when he's in that fight area. Not just the fight area for me, but any interaction it seems to be 40 or below.  
 
The difference isn't drastic from 4000+ x2 to 5000+ x2... at least what I heard. He's also running Vista... I'm running XP.. it should at least be around the same FPS. I'm getting lower.

 
 Your Video settings in oblivion will make a lot of differance to performance. here is a link to a good guide.
 http://www.tweakguides.com/Oblivion_1.html.
    Mactronix

perhaps if you test other games, use 3dmark to cmpare with other users with similar configs you might find an answer.

3dmark is kinda big.. no?  
 
Anyways, just disappointed friend with the same card can max oblivion and max it with the higher textures (2gb or so) patch. I've read threads and people say the x2 4000+ compared to the x2 5000+ is not THAT huge... so I'm at a loss... does Vista help with FPS for that game? I would think it would make it less.
 
So now I gotta lower the settings so much after expecting maxing it out no problem. Damn.. oh well. It's weird how the fps at that place doesn't increase or anything even when I lower the res...  
 
The guide to tweak Oblivion doesn't work. Not found URL.
 
Thanks.

Ok i will try again TweakGuides.com - Elder Scrolls IV Oblivion Tweak Guide
  Try that one
    Mactronix

Ok i will try again TweakGuides.com - http://www.tweakguides.com/Oblivion_1.html
  Try that one
    Mactronix

Yep that works ?
  Mactronix

At max settings oblivion is still a very demanding game, however 16fps inside does seem very low. Are you sure that you dont have any AA enabled.  
 
You mentioned that you are getting 100+ fps in some places....have you found this out by running fraps?
 
If you really are getting 100+ fps then vsync must be off. Even if you have activated it in the game itself it may be forced off in  the nvidia control panel.
If that is off without your knowledge then perhaps you have high levels of AA/ AF enables.  
 
I noticed that enabling transparency AA severely reduced my fps in oblivion (to less than 20fps when people were about ....blood seemed to really hit it)
 
I play at the same resolution with a 4200+ @ 2.55 and 8800gt and even with 4xAA/8AF my framerate never goes below 25.

yeah. it does.
 
im still disappointed at the fact that i can't run it as well as i wanted to.
 
i have to tweak settings lower now.. ugh..
 
i'm pretty sure something is wrong.... this guy on youtube suggested a cheap x2 (like mine) and a 9600gt to max oblivion. even with the nature mod!
 
i dont even want to try other games like crysis or anything lol.  
 
should i just return it?

@ lameness.
 
I'm pretty sure all AA is off... and yeah I enabled vsync and it went locked to 60 fps. With it off, it goes really high in the less demanding areas.
 
It seems as soon as a fight or people come (especially beginning scene)... it can go as low as 17 fps in some areas. Mostly just goes to 21 though.
 
Terrible... I don't know what to do...

Since you have only 2gb of ram, maybe it ran out and started to use page file? That would certainly do it. Not sure how much ram Oblivion use though. Crysis use 2+gb after a few hours, but it's Crysis.

It's probably your AUDIO drivers. Go into the .ini file and turn off the two "sound" lines by changing their number from "1" to a "0".
This should make the heavily sound-laden fight scenes much smoother. If this is indeed the case, try updating your audio drivers.
I play my Oblivion with only the music disabled (set to "0" ) and this seems to help too.
 
Good luck!

Download CPU-Z and see how fast the PCI-Express bus is running at. My friend had this problem a while ago, and it turned out to be a crappy 4x PCI-E bus in a cheap mobo.  I'm sure a crap bus will effectively cripple a 9600GT.
 
Also, a 4000 X2 isn't exactly a fast processor. That would be the first thing I would upgrade.

An X2 4000+ will struggle in parts of Oblivion.  
 
Here is the difference running through a town at max details with an 8800GS.  Notice the X2 5600+ quite a bit ahead of the 4200+.

 
Even outdoors there is often a difference.  Again max details outside int the Forrest:

 
 
That said, 16x10 max details, the 9600GT will also hit some areas where it will struggle.  Tall thick Grass (Foliage) being the worst.  
 
You may want to hit tweakguides as suggested.  A few small adjustments can make a big difference in performance.  Tweak the min grass height.  Set shadow filtering to low.  Turn off self shadows and set interior/exterior shadows to 50%.

Nope, PCI-E is 16x.  
 
Ok. Maybe I'll save up for a processor down the road.
 
Actually, since I already have a good PSU, GPU, and Ram.. maybe I should build my own computer now? HP is ****. Limits me alot. Would buying a case/motherboard be all that I need? Can I just take the parts from the HP computer? Like disc drive, HDD, etc.

sure. sometimes buying a HP is a good way to start. That's what I did with my old Emachine. Bought it (cheap) and then gradually upgraded it until I "moved out of it" I used the hard drives and CD drives after the thing eventually fried. Buy a case and a motherboard and you should be good to go. Keep in mind: some companies use special motherboards and heatsink combos, where the heatsink WILL NOT WORK in any other motherboards. I would wait until you can get the case, motherboard, and CPU combo.