2T vs. 1T on DDR3?

[homebuildit]

I'm sure it's been addressed before, but the search terms are too short for the search to work

Can someone explain, or point me to a write-up of how much better 1T over 2T is for DDR3, and also to explain what they mean?

I see lots of people at 1T. I'm at 2T (9-9-9-24 2T @1900 on 12gb of ripjaws - 2x2 + 2x4). Read somewhere that it doesn't matter much for DDR3, but I'd like to understand much better what I'm looking at.

Thanks.

 

[peanutbudder]

subbed

I am very curious about this too since I have 8gb 2x4 @ 1600mhz 9-9-9-24 2T which I have no idea what the command rate (T) actually means..

 

[Tech Tweaker]

Command rate - is the delay (in clock cycles) between when chip select is asserted (i.e. the RAM is selected) and commands (i.e. Activate Row) can be issued to the RAM. Typical values are 1T (one clock cycle) and 2T (two clock cycles).

Command Rate: Also called CPC (Command Per Clock). The amount of time in cycles when the chip select is executed and the commands can be issued. The lower (1T) the faster the performance, but 2T is used to maintain system stability. On Intel based machines, 1T is always used where the number of banks per channel are limited to 4. Most intel based motherboards don't cooperate well with 1t command rates even if the memory module is able to support it. Most times it will produce memory corruptions (especially with overclocking) which results in very poor performance.

http://www.overclock.net/t/1158709/what-is-command-rate-1t-2t-what-difference-does-it-make

http://www.overclockers.com/forums/showthread.php?t=602764

http://hardforum.com/showthread.php?t=1404398

 

[peanutbudder]

I just changed my command rate 2 to 1 and Aida64 shows about a 5% performance increase on my corsair dominators @1600 MHz 9-9-9-24. Running prime95 to check the stability of the ram.

 

[Bobnova]

I've been running 1t on Intel since I first got an Intel DDR3 board.
That covers 1156, 1366 (three different CPUs), 1155 on both SB and IB.

No issues.

It makes a meaningful difference in memory related benchmarks. In daily use... not so much.

 

[homebuildit]

Okay, so I read those links, thanks for them.

I was going to download and try that maxxmem2, but wasn't sure to trust the downloader software where I found the download by google. So I didn't try that.

But I did try changing to 1T in BIOS. Problem is though, once I enable "expert" ram setting in BIOS in order to change to 1T, it does away with all the other auto timing settings. I can put it back to 9-9-9-24, but all the other settings I don't know where they were on auto. Hmm maybe I can go back in and write them down if they are visible when auto selected.

 

[trents]

"All the other settings" you can leave alone as they have little or no consequence on performance or stability. They will remain as they were under Auto unless you manually change them individually.

 

[homebuildit]

"All the other settings" you can leave alone as they have little or no consequence on performance or stability. They will remain as they were under Auto unless you manually change them individually.

I would have thought they would have too, but when I set it to manual or "expert", it went from 9-9-9-24 to 7-x-x-19 or something. I believe the other numbers changed too, but not sure.

Already over my quota for OC'ing for today, so just running at 2T for the moment, which is quite fine anyway. But definitely looking to optimize, which I assume many others on here are similar to me, that good enough is not good enough, not you can't tell the difference so who cares. By that mentality, I could have just bought a Dell and not noticed the difference

 

[homebuildit]

Oh I get it better now after all this then reading this wiki article http://en.wikipedia.org/wiki/SDRAM_latency

So basically 9-9-9-24 2T should be similar in performance to 10-10-10-28 1T, though I may have the fourth number off some.

A while back (~2010) I had printed and studied an in depth article on how SDRAM works exactly, but forgot most of the terminology, but much clearer now again.

Thanks much guys.

 

[freeagent]

http://www.overclock.net/t/1158709/what-is-command-rate-1t-2t-what-difference-does-it-make

http://www.overclockers.com/forums/showthread.php?t=602764

http://hardforum.com/showthread.php?t=1404398

The quote from EOC was intended for s775 boards. X58 and up have no problem running at 1T

 

[peanutbudder]

Well after changing my ram to 1t made a difference in 3dmark 11 for some reason. My highest score before changing the command rate was 8979 3dmarks I now scored 9016/9020 3dmarks using all the same configurations with the exception of the change to the command rate. Should this have changed my score as much as it did?

 

[EarthDog]

That change is borderline margin of error...

 

[madman7]

I've wondered about 1t-2T settings myself. My memory is at 2T and was looking for a simple explanation about the performance difference of 1T and 2T and also stability issues. I have 4 memory modules set as dual channel for a total of 8gb in all memory slots. Looks like I'll leave it at 2T. Thanks for the info. guys.

 

[peanutbudder]

Well, I ran 3dmark 11 again three times @1t and 2t and the results are the exactly same it shows an increase in performance. While running @1600mhz 9-9-9-24 2t I averaged 8944 for three runs and @1600mhz 9-9-9-24 1t the average was 9013 3dmarks. I don't think its a margin of error since I ran it three times at each setting an saw the same results each time. I mean grated its not a huge gain but it pushed me above 9000 3dmarks which has been a goal of mine for the last few weeks. I ran my 2500k @4.9ghz my 560ti's at 920mhz each and the ram at 1t &2t. Stoked!

 

[Bobnova]

See post #5
In all seriousness, thank you for testing it. It makes me very happy to see someone doing some real testing on a question rather than simply accepting the conventional wisdom.
Conventional wisdom is generally correct, otherwise it wouldn't be the conventional wisdom. It is not always correct though!
Anyway, thanks for the numbers.

 

[madman7]

I might try changing mine to 1T and check it for stability. I can't find what my memory is supposed to be set at. In auto the BIOS sets it to 9-9-9-24-33 2T @1333. I tried Adata's site for settings but couldn't find it. In XMP it should be set at 9-9-9-25-34 but nothing listed for 1T or 2T. CPU-Z never populates the setting for either 1T or 2T.

 

[peanutbudder]

I set mine to x.m.p then changed the command rate manually to 1T and has been stable all day. I've run prime95, 3dmark 11, aida64 without and crashes or problems and im sitting at 4.2ghz.

 

[xoriam]

Just tested this, changed my command rate from 2t to 1t and my physics score went from 9250 at 2t, to 9500 at 1t not to big of a diffrence, but there was a 2fps increase on the test.

 

[peanutbudder]

So, i'm not alone it did help! Sweet!

 

[xoriam]

keep them secrets coming!