Well, I have a q6600 and I have no complaints about computing speed. I play games and do video transcoding occasionally. This processor isn't close to the fastest out anymore, BUT, it fits and works on the motherboard.
If you don't want to upgrade the entire system ie new mobo, ram etc, this is a good upgrade if you can find the chip for sale and at a reasonable price. I picked mine up for $100 US and it was totally worth it.
The precision 390 shipped with 2 different motherboards. One for the Cedar Mill and Conroe CPU's, and one for the Kentsfield CPUs. the Kentsfiled are the quad core Q series, the E6xxx and E4xxx are the conroe series.
Depending on the part number of the motherboard it may not work with the Q series processors.
Hello friends, I am in a similar predicament to Gforcejames. I also have a Dell 390 Workstation, though I have the Cedar Mill Pentium 4 chip and respective board. I am looking to upgrade motherboard and processor to the Core i7 variety. I need help discerning whether there is a motherboard on the market that will fit in my dell case. I wish I could tell you the form factor (i.e. ATX, BTX, etc.), but I am unable to find that info on my own. Thanks a bunch for input in advance.