|The '333' may not be a frequency rating. I came across a reference to PC4200-444. The explanation of the 444 is that it specifies the timing--CL4:|
If that were the case then '333' may mean CL3, a value found in PC3200 ram.
But I also found references to PC3200/333 mhz and PC4200/444 mhz so either I'm wrong or those who posted those figures just assumed they mean speed (mhz) and included it.
I also thought maybe it meant they could run at 333 mhz (PC2700) as well as 400 but they should do that anyway so why include it?
Maybe jam will be along to clear it up.
Help me Jebus!