QUOTEAre they Really Sempron 64 bit.... Not all 754-pin Sempron processors are 64-bit enabled (Socket A Semprons don't have 64-bit capability at all as they're Athlon XP based).
Those 754-pin parts that do support AMD64 (64-bit capability) are pretty much equivalent to a 754-pin Athlon 64, but with a smaller L2-cache and lower clockspeed (and without Cool'n'Quiet support on 'smaller' models, usually <3000+). Unlike the old 754-pin Athlon 64, they also use newer 90nm SOI cores - the mainstream Athlon 64s have moved to the newer Socket 939 platform.
------------------------- The opinions expressed above do not represent those of Advanced Micro Devices or any of their affiliates. <center><font color=red>MODERATOR</center></font> AMD Athlon 64 X2 6000+ 89W :: Asus M2N32SLI Deluxe :: 2x1024MB Muskin XP2-6400 DDR2-800 :: BeQuiet! Darkpower Pro 530W :: 2x WD Raptor 74GB/10k rpm, RAID 0 :: ATI Radeon X1950XTX