As I have read in previous posts, FSX is heavily dependent on clock speed rather than number of cores. Will I see any improvement if I upgraded from my current system which is an AMD dual core X2 6000 (3.1Ghz) to an Intel Core 2 Quad Q8400? My current system has 4 gig RAM and evga 9600 GT Low Power GPU. Thanks for all your advice.

Not a whole lot.... maybe some improvement in smoothness. If you're going to upgrade go with the Core i7 line, like an overclocked 920It's not worth the cost to go from a AMD6000 to that Q.... imho and I use the same cpu as you.Now if you overclock the CPU a lot, like at a minimum to 3.4 it would help....but you'll need a good cooler for that

Thanks for your response.Suppose I upgraded from my current CPU X2 6000 to Intel Core 2 Duo E8600 which is the highest clock speed, would that bring about a significant increase in performance?

K8 is pretty slow compared to Conroe/Penryn. I'd say you could see significant gains, particularly when overclocking.Once upon a time I had an Opteron 175. Dual core 2.2GHz dual 1MB L2 caches, overclocked to 2.5-2.7 (depending upon ambient temps). An X2 6000 is in the same performance class as that CPU, and that's respectable. I had that chip back in 2005-2006. The slowest machine I own/maintain for friends/family is in the same performance class. In a web surfing machine. Upgrades are *cheap* right now. If you really want to do it, might as well spend a few bucks more for a Lynnfield i7/i5 system.

Thanks for all your responses. Folks have been helpful. After much digging, I'll be going with AMD II Phenom 965.