Most powerful CPU made for 3rd gen i-series Intel. I know it's 10 years old now, but for about $50 you can wake up an old PC. (well, within reason, you know...of course it depends on mobo, memory, hard-drive, bla, bla, bla)
And still only pulls about 100 watts, so most OEM CPU coolers can keep up.
05. Jul 2013
Fastest CPU for Socket 754 MOBO
This is as fast as you're going to get on the old Socket 754 MOBO
Actual clock speed 2400Mhz, 512Kb L2 Cache