DDR2 and Command Rate

[Zenoth]

Can DDR2 run at a Command Rate of 1T like DDR was usually able to?

I'm not very familiar with DDR2, I upgraded my system only a few days ago, and I come from the DDR world, never touched DDR2 in the past. I was used to run my previous DDR memory kits at 1T of course. I'd presume that most of the time running DDR2 at 1T means almost instant instability issues, is it? If there are exceptions then could any of you list them?

As you can see I got a 2GB kit of Crucial Ballistix PC2-8500, currently running at 5-5-5-15 2T at 2.2V as specified by Crucial, and it works wonders so far, very stable up to 1134Mhz when over-clocking my CPU to 3.4Ghz. Even though I can't run it at 4-4-4-12 2T like many seem to be able to with that memory (I've tried from 1.8V to 2.35V, and 4-4-4-12 never POSTS), I would like to try 1T, but since I still don't know much about DDR2 I don't want to risk anything. I think that the worst that could happen is another POST failure, and then I'd just have to reset it to 2T after the BIOS recovers the previous settings (which is what I really like about my current motherboard, it does the very first OC'ing stability testing steps for you), but still, I'm just unsure.

So, can DDR2 in general run 1T? If not, as I asked above, are there any known exceptions?

Thanks.

 

[Idontcare]

Yes it can but the usual caveats that go along with any attempts to hit tight timings applies with CR (command rate).

Note Command Rate support for 1T versus 2T is chipset dependant. Make sure you confirm your mobo/chipset combo supports CR settings and the mobo mfg supports it in the BIOS.

On Intel platform, if the chipset and bios allow for CR of 1T to be set then expect to be able to set it to 1T if you are operating less than DDR2-800 speeds. Anandtech reported they could enable CR of 1T at up to DDR2-900 speeds with voltage bumps in one of their recent mobo reviews. (IRC)

 

[BonzaiDuck]

I'm about ready to add a new thread -- reason I came on here again today.

I've been running alternately Crucial Ballistix DDR2-1000 2GB 2x1GB and Crucial Tracer DDR2-800 2GB 2x1GB in my 680i system.

For the OP, I'd also read-- perhaps a different way of stating what IdontCare says here -- that there is "chipset dependency." The 680i (mine is a Striker Extreme) allows for CMD = 1T. some of the newer Intel chipsets either don't allow it, or aren't "comfortable" with it.

This latest set of DDR2-1000's are a replacement for an RMA'd set. See my thread in a minute or so.