Athlon 64 x2 6000+(Windsor) vs. Phenom 9850 64 x4 (Athena Black Edition) @ 2.5Ghz?

I've noticed with my setup the differences between the two (I.e swapped them over) that the Athlon running at 3.0Ghz with memory set via bios @ 800Mhz is faster than the Phenom at the same rate playing heavy graphics dependent games/apps (AMD/ATi Radeon HD 4850).Setting the memory to 1066Mhz(bios) finally kicks the Phenom into gear and takes the gfx card with it(extra bandwidth and all).Here's the fun bit - using amd overdrive utility (the motherboard one not the catalyst one) in auto mode it boosts the Athlon to 3.4Ghz but winds down the Phenom to 2.2Ghz but still shows only 2-3% gain for the Athlon but the Phenom gets a 18-20% boost at a lower clock rate ????.Anyone else seen this with either AMD or Intel chips before?