i solve the problem ...it was the ati radeon 4670...
new problem yeah.
I have a lot of problem with snow leopard (i can not sleep )
now it booting well.
the problem is :
i have 8 gb ram and i need always to write maxmem=4086 , if i write maxmem= 8000 it shut down the pc)
if i update the kernel from blacknight 10.2 to legacy kernel 10.6.6 it find all the ram 8gb 1600 mhz but all application doesn't work.
i try for graphics card (my max resolution is 1440x900x32) and with a lot of kext that i have tried the max resolution that i find is 1280x1024x32...
i tried every kext i have found in "www.kext.com" or insanelymac.com or here but nothing or black screen or kernel panic or 1024x768x32 resolution... my boot loader i PCEFI 10.6 (with PCefi 10.5 the same)
someone can tell me why i have that problem and a solution.
Sorry for bad english , i'm italian....
thanks

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My hardware
Motherboard: Asus M4a77TD Pro
Processor: AMD Phenom II X4 3.0Ghz 945
Ram: 4x2Gb DDR3 1333Mhz (4 GB CORSAIR 4 GB OCZ SAME CLOCK)
HD SATA 1 TB WD BLACK EDITION NON AHCI (FOR WIN7)
HD SATA 500GB WD AHCI MODE (FOR SL)
Video Card: Sapphire HD 4670 1 GB DDR3
DVD ROM - LG SATA