u heard/read right (read close
3700+ is with 754 pins, and 3500+/3800+ are with 939
this 939 pin versions are the newest, as now they have incorporated the FX and 64 both inton one mobo. still they came with one 754 pin version, as now people those who have alredy bought 754 pin series boards, might require higher clock speeds.
Adding: this 3700+ on 754 Pins is with 1MB L2 cache, where all others are on 512-L2, so basically 3700 and 3800 are of same clock, writing both:
3700+ = 754pins 2.2Ghz L2 = 1MB
3800+ = 939pins 2.2Ghz L2 = 512K