There are many Pentium processors, the CPU compatibility depends on the motherboard's socket type and chipset.
1. The motherboard of this system is ECS 945GCT-HM (Livermore), the CPU support list is here:
http://h10025.www1.hp.com/ewfrf/wc/document?docname=c00910113&lc=en&dlc=en&cc=ca&lang=en&product=3377251 * Socket: 775
* Supports the following processors:
o Core 2 Duo E4x00 with Dual Core technologiy (Conroe core)
o Pentium D 9xx Dual Core technology (Presler core)
o Pentium 4 6x1 series (Cedar Mill core)
o Celeron D 3xx series (Cedar Mill core)
o Celeron D 3xx series (Prescott core)
2. The motherboard of this system is the ASUS P5LP-LE (Altair), the CPU support list is here:
http://h10025.www1.hp.com/ewfrf/wc/document?docname=c00714521&lc=en&cc=no&dlc=no&product=3284971&rule=37951&lang=no * Socket: 775
* Supports the following processors:
o Pentium D 900 series Dual Core
o Pentium D 800 series Dual Core
o Pentium 4 600 series
o Pentium 4 600 series
o Pentium 4 500 series
o Celeron D
