Inspiron 1501, CPU upgrade - FSB & Memory Issue?

​I recently upgraded my Inspiron 1501 from the Sempron 3600 processor to a Turion 64 x 2 TL-60 (TMDTL60HAX5DM). The CPU upgrade itself went fine, and everything is up and running. I have noticed since however, after trying to check specs, with only a half education on the area to boot, that my ram is running rather slow based on readout's from both cpu-z and aida64. They both say my effective dram frequency is 160 MHz (319/320 DDR) yet also state i have 667 MHz RAM installed. I currently have a 2 GB and 512 MB stick in, both PC5300/667 MHz. I also notice my dram/fsb ratio changes depending on CPU load - which ranges from 4 x multiplier to 10 x multiplier, when on 4 x, the ratio is CPU/5 (4/5, which at 200Mhz FSB is 160 I assume?), and when running at 10 x, the ratio is CPU/8 (10/8, which as 200 MHz FSB is 250 MHz, which is just off of the 249.4 MHz benchmark I receive when I test...)​
​Anyway, this just doesn't seem to add up, and I am open to suggestions... should I try installing a dual channel 'kit' or is there something I am missing? Any more info you want, just ask!​

​Unfortunately I did not do any benchmarks or specs before I upgraded ,so I have nothign to compare it to. I have seen posts stating that people can not get their RAM to run @ 667 MHz, that maybe there is a board limitation, but what would cause the limitation I am experiencing? It just seems weird!​