Hii there, I'm currently using dell optiplex 960. And it's a MidTower varient. For now, it has intel core 2 duo E 8500 @ 3.16 Ghz processor and I paired it with 2gb ddr2 sticks * 4.so i have 8 gb of memory. And i am using gt 1030 low profile, and it works great. Can I upgrade my processor to i3?
However, as you can see, the e8600 is a single thread screamer, with even faster performance than the first gen i3. This will make it 'feel' faster in certain applications that use single thread speed.
The one thing you will have to change will be the heatsink and fan from the stock 65w version to the 95w version if you install a quad core. But these are really cheap (like $7 shipped used on ebay), and if fan noise doesn't bother you, the 65w one can cool a 95w processor easily if all fans are set fixed to 100%. This is actually how I run all my systems since fan noise doesn't bother me at all.