Looking for some advice on new systems. It used to be easy to know which processor to buy, just buy the fasted clock speed. Now with all the new processors out with multi-cores, I'm not sure. Would it be faster for a single 8 core (e5-2690) 2.9ghz or dual 8 core (e5-2650) 2ghz? Also, say I buy a HP Z820 with a single (e5-2690) 2.9ghz processor and down the road I want to add another processor, will a off the shelf Intel processor work or do I have to buy a processor from HP? I'm looking at them now and there's a huge difference in price. HP wants $3700 to add another e5-2690 when I can buy that chip direct for $2100. I know most of you will say build your own system from scratch but I'm a DP and editor, not a computer guy and don't have a dedicated IT dept. Any advice would be greatly appreciated.