Windows XP SP1 fail with Intel Core 2 Duo CPU + 2 VGA

[Neo]

Dear Sir,
Followings are our configuration, Intel 945 chipset with on board VGA +
external ATI Graphic card , Intel Core2 Duo CPU . After install Windows XP
SP1 & vga drivers, then boot up will hang up on progressing bar..
Any ideas ?
We tested same hardware & drivers under Windows XP SP2 , it works fine to
boot up..

Thank you very much.
Fam

 

[Yves Leclerc]

First thing to check is: make sure that you are correctly connecting to
monitor to the correct VGA connector. If you have an extra ATi graphic card,
you usually disable the onboard VGA adapter.

 

[Neo]

Dear Sir,
Yes, we connect vag & extra ATI graphic card correctly. And if we change
CPU to Intel P4, it 's ok to work with both vga cards with winXP sp1.
but if change CPU to Intel Core 2 Duo, then WinXP SP1 won't work with both
VGA.
but if same intel Core 2 Duo , then with WinXP SP2 , it's ok!

The pb is , why WinXP SP1 won't work with Intel Core 2 Duo CPU + 2 VGA?
Thank you very much.
Fam