Jump to content
Corsair Community

Purpose of sticks higher than PC3200?


emygbabiHad

Recommended Posts

Im curious... Ive been building computers for a long time but one thing still gets me. If a motherboard only supports up to DDR400, why do people buy DDR500 or higher RAM for it? Is it just to better suit them for the future or what? I know that the RAM is backwards compatible and that it will run at 400mhz, but for some reason I don't see the future as a good enough excuse to pay that much more for your chips, so I figured I'd ask because I just cant think of anything as a possible other reason.
Link to comment
Share on other sites

  • Corsair Employees
Well most who do are over clocking! For example with Twinx1024-4000 Modules we use an ASUS P4C800-E to validate the modules at Cass 3-4-4-8 @ 250 MHz. In other words you cannot run the memory faster than the CPU FSB. So in order to run these modules at full speed you have to run with a 2.4C or 2.6C CPU and set the FSB to 250MHz.! You can follow the link in my signature for the bios settings used with a specific module!
Link to comment
Share on other sites

Hmm, the whole FSB thing sets up an interesting thought. Since AMD's processors' bus is independant from memory (or so Ive been told) then does that mean AMD users dont have to worry about their processor's bus speed? Another thing I still need clearing up is... if the mobo is only rated to DDR400... how does it run DDR500 modules at the 500 speed? I also have a question about the bit in your explanation of the 2.4C or 2.6C FSB setting. You mentioned needing it to be set at 250MHz. I dont know how FSB settings are multiplied for Intel's but for AMD its double of whatever your setting is at (meaning hypithetically if it was an AMD chip set at 250MHz then it'd have a FSB of 500MHz). Are Intel's chips then multiplied by 4, for the actual FSB? If you know of a good site to read about all this rather than explaining it all, I'm more than willing to go read that so that you have the opportunity to give help to those with topics not so easily read about.
Link to comment
Share on other sites

  • Corsair Employees
DDR500 memory would not run in 99.9% of AMD systems. In addition, the same holds true for the CPU/Memory FSB. More so with AMD; as the Memory Freq is dependant on CPU freq. Most AMD systems will top out at about 220 MHz or DDR440 with the memory 1-1! With AMD the data path to the CPU is double data rate thus 200 MHz = 400 MHz DDR. And with Intel P4 CPU's there are 4 single data rate data paths. In the chipset with dual DDR 400 chipsets the CPU data paths are split into 2 double data rate paths.
Link to comment
Share on other sites

So with an AMD processor with FSB of 266MHz (like my 2100+ and 2000+ CPUs) that means they wouldnt be able to run anything higher than PC2700 RAM speeds without overclocking? I'll check out that overclockers.com you told me about in another thread over the next few days. Im sure they will have some newbie guides to keep us from getting lost. Im just very new to going this in-depth, but I generally understand very easily what people are talking about as long as I know how things work. I just read the P4 ratios link in the FAQ part of forums so what you mentioned about the P4's data paths makes perfect sense.
Link to comment
Share on other sites

Okay, have my latest question answered due to reading another thread made by someone else (and it wasnt even the subject of the thread either) One of my initial questions still remains fuzzy though. How is it that a board, that's highest "supported" RAM is DDR400, can run the RAM higher than that? It may sound like a question asked by someone who only knows how to open up MS Word documents and AIM on a computer... but for whatever reason my little (or atleast hardly functional) brain just wont, for the life of me, process how its even possible.
Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...