I know DDR1, talk to me bout DDR2

R

Romale23

Gawd
Joined
Dec 12, 2006
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Hey all, Up until now all my systems were DDR1, i know how what rating i want, what timings i'm going after, i know what the default voltages are and how mutch i can push them based on what type of memory it is etc. etc.

I dont know any of this about DDR2,
Generaly i see DDR2 800 or above being what to shoot for, but i have no idea on how to judge the sticks because i dont know whats a good latency rating for them, whats normal and what sucks. Or how mutch this matters

I also dont know what are considers the good brands for DDR2

Or default voltages

Another thing i'm looking for is the diffrence between 1gig sticks and 2,
I'm used to the standard shooting for a gig of ram going with lowest timings/highest clock possible using 2x512s,The timings in particular, last system i built if you went with 1 gig stick instead of 2x512s you took a hit to latency, is that still the case with ddr2 etc. etc.
 
Romale23 said:
Another thing i'm looking for is the diffrence between 1gig sticks and 2,
I'm used to the standard shooting for a gig of ram going with lowest timings/highest clock possible using 2x512s,The timings in particular, last system i built if you went with 1 gig stick instead of 2x512s you took a hit to latency, is that still the case with ddr2 etc. etc.
Click to expand...

The first thing you need to know is that DDR2-800 (PC2-6400) is the highest official JEDEC spec, and equivalent to DDR-400 (PC-3200) in DDR1 when it comes to official support.

There is also DDR2-667 and 533, which were official speed grades before, known as PC2-5300 and PC2-4200, respectively.

When it comes to buying DDR2, 2x1GB kits are pretty much the norm. There's no real performance benefit to going 2x512MB since the 512MB modules are usually made with the same ICs as the 1GB modules, only they are single-sided instead of double sided.

DDR2-800 can be bought at CAS3, CAS4, and CAS5, and if you're going for 2x2GB kits, CAS6.

As you might imagine, the price disparity is pretty significant, with CAS5 DDR2-800 modules being comparatively inexpensive while CAS3 DDR2-800 modules cost nearly twice as much.

The other thing you need to realize is that there's a bigger difference in frequency than DDR1. While DDR1 scaled from your baseline of DDR400 (at the end of its lifespan) to DDR550 or in rare cases, DDR600, DDR2's baseline starts at DDR2-800 and goes up to DDR2-1250.

Since most motherboards allow independent CPU FSB and RAM speed, running at 1:1 ratio isn't required. Meaning that you can buy a 1066 FSB CPU and you don't need 1066 MHz RAM. (technically, that would be a 1:2 ratio anyway, since 1066 MHz RAM runs at 533 MHz and a 1066 MHz CPU runs at 266 MHz, but I digress)

There is, however, a need for memory faster than DDR2-800 if you're overclocking significantly.

One of the more popular overclocking processors right now is the Core 2 Duo E6300 from Intel, and its default multiplier is 7. (7x266 - 1.86 GHz)

That's all well and good, except for the fact that this processor is a monster overclocker, and can frequently do 3.3-3.6 GHz with air cooling and some small voltage tweaks. Problem with this is, since you can't set the multiplier any higher, in order to get to, say, 3.5 GHz, you need a motherboard and memory that can support 500 MHz FSB (DDR2-1000, PC2-8000) or better.

Corsair currently has a few performance parts, here's what they are:

6400 - Standard CAS5 DDR2-800 XMS part. Good for moderate overclocking with standard latencies. 5-5-5-15 @ 1.9V @ 800 MHz.

6400C4 - Slightly faster CAS4 DDR2-800 XMS part, a bit better overclocking, considerably faster at CAS5 than the standard 6400. 4-4-4-12 @ 2.1V @ 800 MHz.

6400C3 - Extremely fast CAS3 DDR2-800 XMS part, based on Micron ICs. Overclocks extremely well with high voltage (2.2+) and relaxed latency, will easily do 1066 MHz and higher at CAS5 with 2.2V, rated at 3-4-3-9 @ 2.4V @ 800 MHz.

8500C5 - Great overclocking part, 1066 MHz @ 5-5-5-15 @ 2.2V. Micron based.

8888C4 - Insane overclocking part, very tight screen, expensive, not for everyone. 1111 MHz @ 4-4-4-12 @ 2.4V. Micron based.

9136C5 - Better than 8500C5, but not quite as fast, usually, as the 8888C4 due to the latency benefit, but it's usually cheaper. 1142 MHz @ 5-5-5-18 @ 2.2V. Micron based.

10000C5 - Fastest currently selling part in the world, that I'm aware of. Micron based. 1250 MHz @ 5-5-5-18 @ 2.4V. Very tough to find, very tough to make, only a few motherboards do this speed.

That's the XMS line. DDR2 default voltage is 1.8V, most companies rate their performance lines at 1.9V, or if it's Micron-based, bumping the voltage up gives you significantly more frequency and heat.
 
Thnx for the time and information redbeard, if its any consilation for your time spent posting it i will be buying corsair on princable due to the customer service i just recieved. If anyone here uses any of these parts some feedback would be appriacted, currently im using OCZ ddr1 running at 3.0V, kinda weary of pumping up voltage agian which it appears i need to do but not as bad, which is good, My memory/processor puts off so mutch heat i had to throw fans ontop of my non overclocked 6800gt to keep it from artifacting. Trying to the massive cooling requirements this time, while stil having a modest overclock
 
Redbeard said:
10000C5 - Fastest currently selling part in the world, that I'm aware of. Micron based. 1250 MHz @ 5-5-5-18 @ 2.4V. Very tough to find, very tough to make, only a few motherboards do this speed.
Click to expand...

Thanks for the info! Could you tell us which MB will support 1250MHz and which MB are you using to qualify this particular memory? Lastly, is it safe to assume that any MB that can handle 1250MHz should be able to handle all other memories that are slower than this; 9136, 8888, 8500, etc...

Thanks again!
 
JimmyNeutron said:
Thanks for the info! Could you tell us which MB will support 1250MHz and which MB are you using to qualify this particular memory? Lastly, is it safe to assume that any MB that can handle 1250MHz should be able to handle all other memories that are slower than this; 9136, 8888, 8500, etc...

Thanks again!
Click to expand...

The only two boards I've been able to use at this speed right now are the eVGA 680i SLI board and the Asus Striker Extreme/P5N32-E SLI. The Asus board will only do that speed with a BIOS update, I'm not sure if it's been released yet, but it's definitely going to be released soon. I've tested a pre-release version, and aside from one major bug, it looks good.

We use the eVGA 680i SLI to qualify the memory right now. And yes, any board that can do 1250 MHz should be able to handle all the lower speeds quite easily.

The real benefit to the higher memory would be the higher FSB possibilities. If your motherboard doesn't crap out, you theoretically should be able to do 625 MHz FSB with the 10000C5 parts, which, if you're on an E6300 and some really crazy cooling, would be around 4.375 GHz. You won't hit that on air cooling, and you might even need to get lucky and get a great board for the CPU FSB to hit that, but there are guys hitting that speed, and they need good memory, so that's why that part exists.

Some of those guys do buy other processors though. The world record guys like the high multiplier processors so they don't have to get too crazy on the FSB. At 11 multiplier, all you need for 4 GHz is like 370 MHz FSB. But then, to hit the SuperPi world records and whatnot, you need high bandwidth RAM too, so those guys like the part.

It's not really a part designed for mass market, we can't possibly make enough to fulfill demand even now, let alone if we started dropping prices down low. It really is like the fastest DDR2 on the market. I imagine with DDR3 coming around the bend, we won't see much faster than 1250. We might get to 1300 or 1333 or something on extremely binned parts selling for even more expensive than the 10000C5, but I imagine there won't be many of them out there, as production will begin ramping up on DDR3 very soon.
 
Thanks Redbeard! The EVGA 680 and the Asus Striker are actually the two MBs I'm looking at. Just waiting a week after Vista launch day tomorrow to see if there are still any major bugs other than what I've been reading on the EVGA and Asus forums.
 
Great info Redbeard way to go the extra mile!

...makes me feel better about my xms memory now...
 
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