GMA3600 / SGX545 questions

Hello,

I've got a mini-itx old board having the Intel Atom D2500 cpu, 0.32um, 64bit, dual core SSSE3, with DDR3 support. Obviously this nowdays is an old low power 10W cpu but I built a home computer with it and I've to say it wasn't that bad all considered. The soc has a GMA3600 GPU based on the SGX545 core I suppose and clocked @ 400Mhz. It is a Directx9.0c (someone even talked about almost Directx10) gpu with interesting features but its story were been someway problematic I remember. It had only Win7 32bit drivers officially with a rare 64bit beta version around while the cpu itself were fully 64bit but at the end it was needed to be used the 32bit version of that o.s. Linux also had a long story behind until it was written a kernel module for most of these netbook cores that nowdays works quite well in 64bit Linux installation not using 3D acceleration cause there is no support for it.
Now, I tried installing my Win 8.1 retail 32bit version on it and forcing the latest driver and reducing the ram utilization (from 4GB to 3GB addressable) the GUI works quite fast and well and the system mostly is stable even if not supported officially.
But I'd like to ask you opinions because games on this GPU, which I had not many expectations from obviously considering it might ask for 3W of power, works in a strange ways.. old Directx6 bench with latest drivers render correctly (example 3dmark2000) but the score is incredibly low (1300 score, 100M fill rate...) while bench like 3dmark05 incredibly heavier results in 726 score, 2781 CPU points, 608Mtexel/s single and 289Mtexel/s multi, Pixel Shader 10,9fps, Vertex Shaders simple 14,6MVertices/s complex 8,4MVertices/s
It seems like old games suffers much more than newer ones that might not be fast but still I wasn't expecting to see games like Doom3 or Far Cry or GTA IV to run at all and instead they did with no errors more or less.
Do you know or do you think the GPU might have been specifically optimized for DX9 features while suffering on older ones? I've seen youtube video of the same GPU running at three times the scores in 3dmark2000 but with rendering strange behaviours.
What do you think about it? Might be the Win8.x working differently than Win7 Starter where it'd be supposed to run?
Thanks

 

Update: just to update this old thread for what I've found that might be obvious maybe but I didn't know that. Beside the really strange performance of the SGX545 which I don't really well understand why suffer that much even on its own Directx9.0c level titles (even early "simple" DX9 games released), it looks like the older Directx7 games runs slow more for o.s. compatibility reasons than the GPU itself. The compatibility of Direct3D old games on Win 8.x seems a problem I didn't know about and the rendering (even 3DMark2000) seems to need to be isolated @ fullscreen from the GUI and using a DirectDraw emulator to really run at higher speed while still introducing I suppose latency that decrease the final speed anyway.
For example the polygons/s tests that in Directx8.1/9.0 bench reach a 20Mt/s in simple tests, in old Directx7 bench with or without compatibility fix or DDraw emulation can reach much lower values from 3.0Mt/s up to 10Mt/s depending on the fix used. Also I'm not entirely sure the T&L unit even if used in those Direct3D7 old tests, when using compatibility tricks actually performs as expected not to mention the multitexturing values lower than the singletexturing one that I don't understand (in every tests, even Dx9 level ones).

Win 7 32bit which the GPU WDDM1.1 driver was oriented to, performs faster than Win 8.1 32bit in older games and I suppose it still use some compatibility fix to run old games even without forcing the compatibility flags the results are higher in every games/tests while Dx8.1 and Dx9.0 results are both similar (still a bit faster on Win7).
So the more correct o.s. to test this GPU remains only Win7 32bit o.s. and I can't understand why even with its WDDM1.1 the Metro GUI and the whole o.s. suffer that much compared to the acceptable Win 7 general speed usage both in the GUI and games but I wonder why the gpu never seen any Win 8.x or later drivers even if I don't understand the technical reasons. I'd like to know your opinion on this old and forgotten GPU used. Which was in your opinion the technical problem that ended its support that soon and could not optimize more its speed?