Hi I was Precision Workstation 490: (this machine is near T7500 in a another post). 
  
the setup: 
-Intel Xeon 5130 2Ghz bus 1333Mhz 4MB cache (2 cores 64bits) 
-2 DDR2 1GB (ECC)  2GB finaly 
- Nvidia Quadro FX3500 256MB 
  
I Was install myhack lion 
My problems: 
reset cmos 
no shutdown 
  
The file dellprecison490.zip which have dsdt extract by DPCIManager. 
  
I work to have FX3500 patched with QE. 
Can anyone help me with DSDT bug? 
DarwinDumper_2.4.9_Chameleon_2.1_Lion_viking 2.zip 
DELL Precision 490.zip