|This may make things even more confusing, but it usually makes things easier to speak in terms of frequency. Bus speeds are theoretical/advertised speeds, frequencies are actual speeds. You also need to know a little CPU history & theory.|
Intel "quad-pumps" the FSB so to determine the actual frequency, just divide by 4. For instance, your P4 runs at 533MHz FSB, so the frequency is 533/4 = 133MHz.
All DDR Ram is "double-pumped" so to determine it's frequency, divide by 2. DDR333 has an advertised speed of 333MHz, so the frequency is 333/2 = 166MHz.
The vast majority of systems perform best with the CPU & RAM running at the same frequency...this is known as 1:1 ratio. However, the P4 is a highly inefficient CPU & it was determined a long time ago that it performs best with the RAM frequency faster than the CPU frequency. The two best ratios are either 3:4 or 4:5, depending on the CPU's default frequency. 400MHz & 800MHz FSB P4's should be run at 3:4, 533MHz FSB P4's should be run at 4:5.
What this all means is the best RAM to pair up with your 533MHz FSB P4 would be DDR333.
BTW, have you opened your case & examined the board? Acoording to Crucial AND Intel, it only have 2 memory slots & supports a max or 2GB, 1GB per slot. Where did you get your info from?