The Motherboard and Power Supply do not support "Pentium extreme edition" 960 is max. If you want to use that processor you need Dell Precision T3400 with 525W power supply. The T3400 also supports 16 gigs of ram vs the GX620 3.50 gigs max. [IMAGE]      
Hi, I have an optiplex gx620 currently running Windows 10 from Windows XP with a Pentium 4 HT. For a Processor upgrade I know the Pentium D series is recommended and a Pentium D 960 can be used with a copper heatsink, so my questions are could it run a Pentium extreme edition and what is the highest Pentium D it could run without upgrading the heatsink. Thanks, Matt
Optiplex gx620