800mhz RAM for T61

Does the T61 support it? It's hard to find, but it's there...
http://www.ec.kingston.com/ecom/configurator_new/partsinfo.asp?ktcpartno=KVR800D2S5/1G

Do you see any reason why it wouldn't work???

 

Nope. As I understand it, Santa Rosa introduced the ability to use 800MHz RAM. Although I don't know what the specifics are.

 

After I added the RAM to my cart, I see now that it isn't available until 6/4/07. I wonder if that means that we might see several manufacturers release 800MHz RAM. I wonder if Santa Rosa supports 800MHz DDR3 RAM. Hmmm gonna try to find out now...

 

Santa Rosa supports up to DDR2-667. You can stick DDR2-800 in there but it will run at reduced speeds. It was commonly thought that Santa Rosa would support DDR2-800. Indeed, many reviews are touting DDR2-667 as a 'con'... which makes absolutely no sense since any higher is not supported and only shows ignorance on the reviewers' part.

And no, you cannot use DDR3 of any kind. I don't think there is even such thing as a DDR3 SO-DIMM.

 

No... I know it's not yet. I just read various information from intel.com and wikipedia. They all confirm that Santa Rosa supports DDR2-667. But I wonder if that is just because DDR2 800MHz SODIMM just isn't available yet? How could they say that Santa Rosa supports something that isn't available (even though it is inevitable)?

 

If I still remember how DDR memory works, then DDR2 800 isn't necessary. In fact, you'll be paying for more than you'll actually use. The FSB of Santa Rosa is 800Mhz. DDR2 667 supports up to 1334Mhz of FSB (667Mhz x 2). It's multiplied by 2 because it's double data rate. With that said, DDR 800 will support up to 1600Mhz FSB.

 

So then I might as well go out and buy DDR2 400 memory because it will support up to 800MHz FSB and I will get no performance benefit with DDR2 667?

 

The FSB speed and the memory speed are not linked. Santa Rosa has a max FSB of 800 MHz and a max memory speed of 667 MHz. You will definitely get a speed increase from 400 MHz memory to 667 MHz.

DDR3 memory will not be possible until the next iteration of the Centrino chipset, Montevina, in 2008. The advantage of DDR3 will be its higher speed and lower power usage.

Check Wikipedia: http://en.wikipedia.org/wiki/DDR2_SDRAM

Standard name Memory clock I/O Bus clock Data transfers per second
DDR2-400 100 MHz 200 MHz 400 Million
DDR2-533 133 MHz 266 MHz 533 Million
DDR2-667 166 MHz 333 MHz 667 Million
DDR2-800 200 MHz 400 MHz 800 Million
DDR2-1066 266 MHz 533 MHz 1066 Million

As you can see DDR2-667 only needs a 333 MHz clock to reach maximum speed.

 

The key thing you are missing is something called a DDR to FSB Ratio.

Memory Speed and FSB are not linked, but still provide performance increases depending on how they are mixed. DDR also adds to the confusion since as stated above it multiplies the speed since it is Double Data Rate.

Santa Rosa is big since it runs the FSB at 800mhz, this does not mean memory, but because it does not mean memory does not state there is no performance increase.

It is complicated, I do not want to try and explain it as others have explained it better on the net, but if you look into OCing guides you will find a lot of the info about how it all works out.

 

that sucks we have to wiat that long to take advantage of it. Looks like Samsung is set to release already

http://www.pcworld.com/article/id,131779-c,ddr/article.html

 

DDR3 is typically higher latency than DDR2 at the same speeds, so unless they can support much higher frequency DDR3, it won't be worth it - not to mention the substantial price premium.

Theoretically, putting dual channel DDR2-400 alongside an FSB of 800MHz would be perfect. However, those are theoretical numbers. Due to many variables, you're not going to reach those performance numbers. As a result, pairing it with faster memory, DDR2-533/DDR2-667 does a lot to saturate the FSB bandwidth. Going higher and higher will still net you some performance, but (especially) above DDR2-667, performance gains are minimal on a 800MHz FSB. You might get another 2-5% in very memory-intensive apps.

It's not a big factor for performance. As long as they're not shipping DDR2-533 and lower with these Santa Rosa's, I wouldn't count it as a con.

 

DDR2 400 will probably be more expensive than DDR2 667 even though DDR 400 is slower. It's just supply and demand.