Hmm here something new I did not know about directx11 and DIRT 2.
Hardware Tessellated Dynamic Water is only enabled with ULTRA quality settings and with Direct X 11 the hardware tessellator is used to generate hundreds of triangles dependant on how close to the water the camera is.
Read more: Dirt 2 DX11 Performance - ATI - Introduction - DriverHeaven.net http://www.driverheaven.net/reviews.php?reviewid=902&pageid=1#ixzz0Z2JE48P1
The Hardware Tessellated Animated Crowds only make an appearance once again with settings on ULTRA and the idea of this is to create a more realistic looking environment with people on the edges of the race tracks.
Read more: Dirt 2 DX11 Performance - ATI - Introduction - DriverHeaven.net http://www.driverheaven.net/reviews.php?reviewid=902&pageid=1#ixzz0Z2Jk0OQz
The Hardware Tessellated Dynamic Cloth is triggered by the HIGH setting in game and while it is not often immediately noticeable in game as you plough around the track if you pay attention you should notice plastic sheeting and various banners and cloth surfaces in the crowd and environmental areas.
Read more: Dirt 2 DX11 Performance - ATI - Introduction - DriverHeaven.net http://www.driverheaven.net/reviews.php?reviewid=902&pageid=1#ixzz0Z2JuGBO6
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So just having a video card that has directx11 hardware is not enough to see the new eye candy in PC version of DIRT 2. You will need CPU and video card that fast enough to run DIRT 2 at Ultra settings at the resolution you want to run DIRT 2 at.
If have a say a LCD monitor with a native resolution of 1680x1050 and quad CPU and a 5770 directx11 video card, can you get avg 40 FPS with Ultra settings? And there posts about if go online you will get hit with a noticeable drop in FPS, so 40 FPS is 25-30 FPS.
I'm glad I still have a CRT monitor, I can still use a 1024x768 or 1280x1024 resolution without monitor degrading the image like a LCD can if not running in it native resolution. I never seem to have fast enough hardware to run the newest games at a high resolution like 1600x1200. I'm still running GRID at 1280x1024 online with Ultra settings and 4xAA with my upgraded 4870 video card. At 1600x1200 I feel there some slight lag online.
This might explain why there posts that say there not much difference between x9 and x11 mode with a 5000 series video card. They maybe not able to run with Ultra settings and still get a good frame rate.
edit:
Moving to 1920x1200 with 2x Anti aliasing proves more of a test for the lower end cards however incredibly the 5770 still manages to hold the frame rates above 25 at all times - there are some noticeable juddering issues however and with this card it would be advisable to disable AA entirely for the best experience. Adding a second 5770 totally smooths out the gameplay however and would be an ideal lower cost upgrade option for a high resolution screen. The 5850 and all cards above it have no problems at this resolution.
Read more: Dirt 2 DX11 Performance - ATI - Dirt 2: 2xAA - DriverHeaven.net
http://www.driverheaven.net/reviews.php?reviewid=902&pageid=3#ixzz0Z2SVqrLR
Note this is not a quad CPU, test uses an Intel 975EE @ 4ghz.