Could my GPU be faulty or is it my PC?

Hey I'm new  

Basically; I have a Sparkle GTS 450 1024MB DDR3 Card (SXS4501024S3NM); however the performance is nasty; especially compared to other cards. I know DDR3 will limit the card even thought it is on a 128-Bit bus but it feels like it's running more like a 64-Bit POV Model  

3DMark06 it only scores 7600+ and Vantage only 4,000 but other users manage to crack 14,000 on 06 and 8000 - 12,000 on Vantage  

I've also noticed in GPU-Z and nVidia Control Panel the Shader Amount, Clocks and Bandwidth are totally different to the site, lower in fact so I'm curious if my card is a duff or my PC is having something to do with this  

I only really use this to play old games like Unreal Tournament 3, Sims 3, Dawn of War II etc etc

My PC:
AMD Athlon 64 X2 6000+ @ 3.00GHz
2GB DDR2 667 Ram
120GB Sata II HDD
Sparkle GTS450 1024MB DDR3
Windows 7 Professional 64-Bit
BETA Drivers: 295.51
600W Corsair GS600

GPU Z Readings:
ROPs: 16
PCI E: 1.1 x16 @ x16 1.1
Shaders: 144 Unifed
Pixel Fill Rate: 4.2 GPixel/s
Texture Fillrate: 16.8 GTexel/s
Memory Type: DDR3
Bus Width: 128 Bit
Memory Size: 1024 MB
Bandwidth: 16.0 GB/S
GPU Clock: 700MHz
Memory: 500MHz
Shader: 1400MHz

Clock rates advertised for the 2GB Model (basically same as mine but double the Memory).
Core Clock: 783MHz
Shader Clock: 1566MHz
Stream Processors: 192 Processor Cores
Effective Memory Clock: 1200MHz


I can attach any Screenshots or give more information if needed   Would like to know if this card is actually preforming right or something is wrong  

Thanks!
Nathan