No there's NO reason what so ever to run them at 1333MHz, thats a fine CPU, its just getting old. But it handles 1600MHz ram no problem at all at stock settings. If anything u could OC your ram to 1866, but that might mean raising the timings from CL9 to CL10 and increacing the voltage. You would have to look around to find the timings to use in BIOS.
When I OC'd my ram, I just looked up the same brand of ram and model of ram, but at a higher speed, and then just used their timings.
And in the meantime whatever u do, those pII-965s usually OC well, so OC it and its NB. Should be hard to get 2000MHz from the CPU-NB with a bit of extra voltage, go read up on pII overclocking, its fun (if u haven't already)
In my memory lane flashback, I missed
Don't really need this thread anymore, found the optimal settings to run it at to keep my overclock stable.