This had been a issue that bugs me for a long time. And I confirmed is a problem for HD4200 when I fixed my laptop for my bro with Intel GMA3000 I guess or 965Express Chipset.
My specs are
AMD Phenom II X4 945
Asus M4A785TD-M EVO
HD4200 with 128MB side port(But it didn't showed in GPU-Z, correct me I'm wrong, it showed 112MB DDR2 on PCI interface) with 32MB Shared
Running on 1920x1080
Windows 7 64Bit
My laptop specs
Intel Celeron-M 560 2.1GHz Single core
Intel GMA3000/965Express with 8MB shared
Running on 1280x800
The laptop ran the windows 7 aero very well, not a bit of lagging, my desktop, if I enable 32MB shared for the HD4200, It runs smoothly, but if I disable it, aero will run very choppy, I wonder why this happens, I already had the latest driver, even though having issues while installing. I thought the HD4200 has the 128MB DDR3 side port and suppose a lot powerful than the 965Express given a quad core is powering it, and yet it will be choppy if I disable the 32MB shared memory, and the 965Express only use 8MB of shared video memory.
And also why is it the GPU-Z show DDR2 and running on PCI?
Okay to summarize it, HD4200 is slower than 965 Express in Windows 7 Aero.
How could this be happening?
And also GPU-z is showing 112MB DDR2 and runs on PCI interface, this doesn't make sense cause it should be DDR3-1333 and i don't think it runs on PCI interface since it is integrated.