DDR2 533/667/800

DJH@GB-Ro · Post by **DJH@GB-Ro** » Thu Apr 05, 2007 3:02 am

Hi, I can't remember where and can't find it again, but I read somewhere that unless you are going to do OCing then 800 will just run at 533?

Can anyone shed any light on this?

floffe · Post by **floffe** » Thu Apr 05, 2007 3:49 am

I'm assuming you're talking about the memory being used together with a Core2, which have a FSB speed of 266MHz*4. That's equivalent to DDR2-533 in bandwidth and sync, while 667 and 800 are not. 800 still performs better though, with 667 being the worst of the three. Oh, and if you overclock you can keep running the faster ones within spec, which the 533 won't.

DJH@GB-Ro · Post by **DJH@GB-Ro** » Thu Apr 05, 2007 5:39 am

Yes, to go with an E6600. So I should just stick to the plan for DDR2-800?

angelkiller · Post by **angelkiller** » Thu Apr 05, 2007 7:34 am

Found the article. Linky You don't want DDR2-667 unless you're overclocking using a 1:1 ratio. DDR2-800 has minimal gains over DDR2-533. They say DDR2-800 has more OC'ing potential, but I don't see that. If you are running a 1:1 ratio, DDR2-800 will only run at it's stock speeds with a 400MHz FSB. That's a huge OC in any case. And only extreme enthusiasts will have more than a 400MHz FSB. So is DDR2-800 really necessary? I don't think so. (When using a 1:1 memory to FSB ratio) If I'm not clear please ask.

DJH@GB-Ro · Post by **DJH@GB-Ro** » Thu Apr 05, 2007 7:49 am

So would I be better off getting:
http://www.ebuyer.com/UK/product/63623
instead of:
http://www.ebuyer.com/UK/product/98710 ?

angelkiller · Post by **angelkiller** » Thu Apr 05, 2007 11:17 am

I think it depends on what you're doing. If your OCing the DDR2-667 will be better because it will run at stock speeds (or near stock speeds) when you OC. In some situations, the DDR-2 533 is faster than the DDR2-667. BUT the DDR2-533 was running a 3-3-3-8, which is pretty tight. (and expensive.) For a genral system, it probably would not matter, nor would you actually notice the difference. I'd get the cheaper memory because it's cheaper, and the difference between DDR2-800 and DDR2-533 is not really noticable. (Assuming you don't OC.)

And going back to your first post, DDR2-800 will only run at DDR2-533 if your FSB to Memory ratio is 1:1. To run the memory at it's default speeds in that case, you would use a different ratio.

sjoukew · Post by **sjoukew** » Thu Apr 05, 2007 2:16 pm

I don't know which review it was, tomshardware xbitlabs or anandtech, but they tried all options, and ddr800(best timings) but the results are comparable to the madshrips article linked above.
The FSB is 266*4= 1066 and the ram is 533 *2 (dual channel) also 1066. That means that the fsb can't move more data then the memory at 533 mhz can deliver, all the extra memory bandwidth is mostly going nowhere. Unless you are overclocking the fsb, nothing is going to change that.
And running a fsb : mem as 1:1 is optimal. any other devision is less optimal, because the chipset has to deal with that difference and make up for it. And clocks timings out of sync is never been optimal, and it will probably never be so.