DDRII Latency Advice

[stocky]

I've been looking into this DDRII business, and it all looks a bit poor compared to BH-5 DDR memory.

What are the actual advantages of DDRII over DDR?

Is there anything out there that will rival original BH-5 DDR memory in DDRII format?

Cheers

 

[bennywidag]

The advantages are the increased bandwidth, they can potentially carry much more data per clock than ddr. also as long as you dont get pc4200 which is just a bit better than 3200 for ddr, (muskin sticks excluded) you will have great clockability, most will be able to go up to a 340Mhz FSB, and new pc8000 does something like 500mhz fsb. in reality however people just run a divider so the ram runs at something like this but the cpu is at 300fsb max.

will write more 2morrow if needed, i have only just got out of bed with flu

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[stocky]

Cheers for that, any info on the latency - can any get near to as low as 2-2-2-5 yet? What is the best stuff for low latency at the moment?

 

[Thickbrit]

ddrII will be a shock to amd users.It runs lower voltages,1.8v stock vs ddr1's 2.5v and consequency runs much cooler too.It may not be able to do 2-2-2-5,but can do some impressive things all the same.3-2-2-8 to well beyond 300mhz,500mhz+ with accceptable timings(acceptable for intel anyway).Best ddrII comes from mushkin,corsair and patriot/pdp.My patriot xblk's can do 450+ mhz at 4-3-3-9,which from an intel perspective is better then ddr1 with slack timings at 3-4-4-8 and prolly struggling to hit 300+.I can also run 3-2-2-4 which is very similar to bh5 timings at around 300mhz.Yeah,i kinda like ddrII.

 

[bennywidag]

Yer, patriots are the best for low latency, ive got corsair pro 5400, which does 340mhz at 4-4-4-12. i have never altered the timings though so it may go faster. the new breed of stuff is very impressive, stuff like 8000 (500mhz) at 3-4-4-8

 

[maverik-sg1]

So are we saying that we run the CPU at 300mhz and the RAM at 350Mhz - thus using a divider to allow more clocks per cycle and more data per cycle on the DDR2 ram whilst still keeping latencies relatively low.

The reverse of how we sometimes do it now? I guess the value is that we lose latency but gain because the data is waiting for the CPU not the CPU waiting for the data, this improves something?

Just trying to wrap me head round it all.

Mav

 

[bennywidag]

Kinda, its a whole different world to AMD mav mate.

lets say you run the cpu at 250mhz, the ram comes as stock on the motherboard to run at 3:4 with the cpu, thus meaning the ram is actually clocking at 333.33 recurring mhz, 250x4/3. i am sure you can do the same thing with a amd actually. however there is another option to allow you to run 2:3, which is handy if you dont want to overclock the cpu, thus running the ram at 300mhz at stock cpu, which gives a significant yield over it running at 200mhz.

the only thing with it is the latencies which are now being ironed out, and all the above is at stock volts by the way, corsair guarentees it to that at stock v. when AM2 comes out it shouild be interesting as they will be using ddr2, and hopefully with tighter latencies.

again sorry if none of this makes sense, im off to bed

 

[Thickbrit]

Yes, on the p5wd2-p you have deviders to underclock and overclock the rams in relation to the cpu.With my cpu at 300 mhz fsb,i have the following ram/cpu frequencies available......

450mhz(225) = 3/4

600mhz(300) = 1/1

750mhz(375) = 5/4

800mhz(400) = 4/3

900mhz(450) = 3/2

1000mhz(500) = 5/3

1200mhz(600) = 2/1

 

[SAS91]

the value is that we lose latency but gain because the data is waiting for the CPU not the CPU waiting for the data, this improves something?

Mav

Thats how ive always seen it, will definatly be interesting when m2 is about