My opteron 170 is a dog that won't overclock well

I purchased a jetway 939 motherboard that has some nice oc features on it. And I bought an opteron 170 off of ebay (and it actually works good, but !!) I can't get it to go highter then 2120 with stock cooling and voltage. I even tried lowering the ddr400 memory to ddr333 (and then ddr266 just to make sure memory wasn't an issue). I then tried upping the voltage and had to go to 1.55v. I then got the cpu to 3100. I didn't like the idea of going higher in voltage then 1.55v . I don't know if the transport speed is important for overclocking so I lowered it to 600 (and even increased the north chipset voltage, LDT voltage, and ram voltage. Still the same results. So I put everthing back and set the fsb to 210. The cpu is now at 2100 (which puts the ram at ddr420). It runs with no problems. I found that I can run the pci-e bus speed from the stock 2500 all the way to 2900. I don't know if it makes a difference, but I'm using a geforce 8800GTS OC from BFG. I ended up setting that at 2800.
Is there something I'm missing as far as trying to overclock this thing? I was hoping to get atleast 2.4 out of it. And How does it effect the speed of the computer overall if I have the ram running at ddr370 (instead of ddr400) just so I can have the cpu run at maybe 2.4 (just as an example)?