Hello, I have a 2.66 GHz Pentium 4 with a 533 MHz FSB (got a good deal on it). The motherboard I'm looking at says it supports Intel Pentium 4 processor with a 400/533/800MHz FSB. OK, my 533 should work fine then. It says it has support for DDR 400/333/266. So which do I need? Our local geek says I should get the DDR266, because 266 x 2 multiplier = 533, to match the processor. Er...multiplier? Sorry, but he's a little over my head there. I thought it was called DDR "266" because it ran double the rate on a 133 MHz bus. Now I've got to figure out some other multiplication to get to 533 MHz? Oh dear, I'm so confused... I think the technology behind DDR is cool. But it was so much simpler to figure out what kind to buy before DDR. And I don't even want to start on this "PC2100" crap. That's just marketing numbers to make it look better against Rambus, right? Could somebody help straighten me out? Is DDR266 really what I want to buy? Would there be any advantage to buying DDR333 or 400? Any advice would be greatly appreciated. Thanks. Daniel

Daniel, take a look at this site....it might help you to read this. Not complicated and even has examples. http://www.upgradingandrepairingpcs.com/articles/2002/upgrade12_02_02.asp

Back to your question? yes, if your motherboard says that supports DDR533 then you could get the DDR266, I think what's confusing you is the terminology used to refer to it. For instance, PC2700 is DDR166 (at least is commonly used this way...)Your DDR266 will be something like PC4300, again is just pure selling lingo. Check the table in teh link I posted...again: http://www.upgradingandrepairingpcs.com/articles/2002/upgrade12_02_02.asp Good Luck

Sorry...on the above I meant: PC2700 is DDR running at 166 mhz, but is not DDR166....my bad...teh same for your case: DDR running at 266mhz with 2 cycles = 533 roughly speacking.....I see where you confusion comes from....even myself sometimes get a little out there....in space...I have done this memory thing many times...but again...too much lingo going on... Good luck

Intel quad pumps their FSB, that is why the memory doesn't match the FSB. AMD FSB is just double pumped, resulting in the same bus speed as the DDR memory ratings. 266 is the memory you need for that MB.

OtheHill nailed it... The base FSB clock is 133mhz, quad-pumped, 133 x 4 = 533mhz FSB The memory is only double-pumped, 133 x 2 = 266mhz Essentially, what your "local geek" told you was correct, he just didn't explain it very well... I think the only advantage to getting DDR333 memory or higher would be if you wanted to overclock, & your DDR266 was holding you back.

Thanks everybody for all your help and explanations. I feel better about knowing what to buy now, and a little more knowledgable about what it all means. Thanks again! :-) Daniel