Quick QUestion about DDR2's above 800mhz

I've noticed expensive DDR2 modules with specifications higher than standard.. such as this

Corsair Twin2X1024-8500 DDR-2
http://www.pcstats.com/artvnl.cfm?articleID=2005

I understand CAS latency (5-5-5-15) which is a big factor in speed, and oc'ing etc etc.. but what i can't seem to get a grasp on his the bus speed higher than what motherboards support currently. i havent seen a motherboard's DDR2 slot with native spec higher dan 800Mhz..

In my understanding this extra bus speed on these modules are for overclocking, where you have more headroom to push these RAMs further..

am i correct? or totally out of mark? hehehe

tea

You're correct. Ram over ddr800 allows for overclocking headroom. Say you have a C2D overclocked to 400mhz fsb & you use a 4:5 divider, the memory would be running 500mhz or ddr1000.

Some guys are getting their e6300's up to 500mhz fsb too, so that would be running ddr1000 1:1.

I think there are some motherboards with upward dividers supporting ddr1066+ too.

Some more to read:

Very few mainboards support anything over DDR-800 by default... and anything faster then 400MHz(800 effective) is worthless in most cases. Unless...

Latency is responsiveness, Hz is bandwidth; and you always have to make a trade-off. A low cycle latency ensures that the CPU will not have to wait for the data to arrive, bandwidth... is generally not as important if the latency is not very impressive.

DDR800 with CL3 can OWN DDR1000 at CL5 is almost every situation... but what if you were Running Photoshop with many 10'000x10'000 uncompressed images? Well then, bandwidth would be more of a concern.

At the moment, ATi's RD600 chipset is the fastest, and with it you can get some extreme memory performance, I've seen the FSB hit 600MHz(500 on stock if you don't want to hit 70c), and with that you can run DDR1200 with 1:1 and still be able to hold some low timings.

the higher ratings are indeed for overclocking, but you can also buy lower rated ram and overclock that.

and if you buy the right stuff, you can have the best of both worlds, ddr2-667 @ ddr2-1050 @ 4-4-3-6:

fountain of enlightment right here. thanks ya'll

Don't let the lower latencies tie up you speed. Especially with DDR2 you want the highest speed you can get over worrying about latency. With the intel group you will want to get the highest FSB and ram speed together even if it means dropping the CPU multi one notch (cool the NB, it will need to stay in the 40s or less). For the AMD bunch you will want the highest CPU speed since FSB is not a factor in ram. This has been hashed a lot. Running the tightest LAT's is cool for benching and bragging rights but has little benefit for gaming and high end processing. Still try for the tighter lats but just don't let them get in the way. I always look the LAT's this way, (DDR800)
CAS, choice is limited CL5, CL4 or some CL3
Ras/Cas, I attempt to run same as CAS but will raise by 1 if I need the rig to be super stable.
tRAS, I tend to use the same number as R/C as we start to see diminishing returns by trying to round corners here.
trc or trcl, bank cycle time is best kept high as this is the number that will cripple the first two listed here is it is to tight. I use 1 number higher than what the bios picks in some cases. Liken this number to charging your cell phone. It's the ram cell charge time. If you don't let it run long enough then expect dropped cells too long and you're wasting cycles. This number plays a smaller effect in testing as it only occurs during the refresh cycles evert 6-12 Micro seconds (remember ram runs at nonsecond speeds).

hUMANbEATbOX said:

the higher ratings are indeed for overclocking, but you can also buy lower rated ram and overclock that.

and if you buy the right stuff, you can have the best of both worlds, ddr2-667 @ ddr2-1050 @ 4-4-3-6:

Click to expand...

amazed at your temps. how do you keep em so low?

[img=http://img244.imageshack.us/img244/7121/imgp0942fn2.jpg]



The corsair dominators are so dam flexable I find they can run at:

3.3.3.8 at 880Mhz
4.4.4.12 at 1111Mhz
5.5.5.15 at 1315Mhz.

Anything above 800Mhz is considered an OC even the 680i does not "officially suport RAM above 800, yet it can push my modules to 1315.

I hear C2D responds better to the higher speeds but I think its also applicaion specific.

y is the pic so big?

Kishin said:

amazed at your temps. how do you keep em so low?

Click to expand...

that was with -30c ambient temps.

hUMANbEATbOX said:

that was with -30c ambient temps.

Click to expand...

Go ahead, show them the pic you showed me.

How did you get gold Heat sinks on those dominator's? I'm about to order some dominator's myself, along with my 8800GTS640. And soon my new CPU and Mobo as the sig implies. Would love to get my RAM up to 1315Mhz.

inkfx said:

Go ahead, show them the pic you showed me.

Click to expand...

that's gettin' too OT.

i'll give a link tho: http://farm1.static.flickr.com/138/372428878_e127c2baba_b.jpg

You cant get gold plated dominators anymore...

The dominators were all tested out on 680i MBs before they were sold apparently dominators run well on 680i MBs.

You can push the dominators to 1315 but you have to have relaxed times of 5.5.5.15.