are you sure? what BIOS and revision is it?
i have a Sempron 64 2800+ that i am overclocking from 1.6Ghz to 2.08Ghz on stock voltage... (i will be stepping it further, to get more ram bandwith, as i put the ram on a divider down to DDR333, and clocked it back up with the FSB to about DDR406, but i KNOW it runs stable up to DDR460 on stock voltage.)
in the BIOS, if it's an Award BIOS, under the Cell Menu, there should be an option change the CPU Bus... the default is 200 (the multiplier on the latest AMD revisions is locked, so you can't raise it.) so, the 3000+ is set at 200x9 = 1.8Ghz... you should be able to raise the FSB... step it til it gets unstable.. then pull it back to the last setting where you were stable...
then, if you want... try putting the ram on a divider, in the BIOS where you can set the DRAM timings, if you change the base from 200 down to 166 (if you have PC3200) you can push the FSB on the processor higher, and the ram will compensate as tho it were DDR333 + the CPU overclock... instead of DDR400 + the CPU Overclock... and you will get more from the CPU while the ram stays stable...
if you push the FSB too far, remember to lower the HT multiplier... i had my HT as high as 1900mhz, but it's a little iffy at those speeds, since stock 1600mhz..
my setup: (still stepping my overclock, to get some more out of my RAM, but for now, it's stable like this)
CPU - AMD Sempron 64 2800+ 1.6Ghz (OC'd to 260x8 = 2.08Ghz) HT x3 35C idle, 43C load
RAM - GeIL PC3200 CL2.5 (divided at DDR333 + FSB Overclock = DDR406)
MOBO - MSI K8N Neo-V nForce3 250
