I found this post on BigResource....trying to research this further on Intel's website...
Agreed with the above. Q9300 is basically a 5420 with half the CPU Cache, so if you're going for 54xx series, try to aim at 5420 or higher. If the Q9300 will offer considerable savings, just go for that. I don't know how often it's done, but we don't often upgrade
servers by adding a second CPU. It's almost always either there when ordered, or never ordered.