DDR 2 - PC1066, this, what??

[KingJimi]

Hello people, I've been away from computers for a while, and I've come back, modding away like there's no tomorrow. Next in line is the Core 2 as upgrade from the Opteron 165 I'm using. But I have a serious problem, because I'm confused as to what DDR-2 memory I should be getting. Everyone says the PC-1066 -- what does all this mean? Having DDR for so long has made me ignorant to the DDR2 available. Please can someone explain to me the differences? The only fact I know (or at least I think it's a fact) is that higher latencies are of a benefit, rather than lower, which I find odd.

Help...?

[oralpain]

1066Mhz DDR2 is PC8400-8500.

You do not need absolute cutting edge DD2, esp for a Core 2, which actually like a 1:1 ratio. Well, not unless you plan on at least a 100% OC (and have a mobo stable at 533MHz FSB).

Higher latencies are always worse. Current DDR2 as lower absolute latency than DDR because it runs so much faster, and this counters crap (relative to DDR) timings. Higher MHZ and lower timings are still the way to go, if possible.

I would recommend some CL4 DDR2 667MHz or 800MHz, if you are on any kind of budget.

Also, check out some DDR2 and Core 2 Duo reviews.

[Clunk]

If you plan on overclocking, get better memory, If not, 5300 stuff will do you fine.

Also, if you go with an E6300/6400 processor, you will need faster ram to achieve the same overclock as, say an E6600.

[cougarslam]

you will also need to apply to your bank for a loan if you want to buy ddr2 8500

[nvening]

Latency does not have much of effect of c2d because of its large ammount and good managment of cache.

Basically the normal speed for C2D is DDR 533

Alot of people will be going for for some DDR 667 as this gives some gaurenteed overclocking potential and indeed many sticks at this speed are capable of more.

Gskill are the current C2D RAM kings imho

[jackvdbuk]

super talent and a-data are the kings for me

[Kumagoro]

I have also been confused by the quoted speeds with respect to C2D.
Possibly by intel in general. It says 1066 MHz which makes you think you
need 1066 MHz ram.

Am I right in thinking that the matching ram speeds for a 1066 MHz C2D
is actually DDR2 533 and because its quad pumped its actual frequency
is 266 MHz?

So RAM clock 266 MHz i.e DDR 533 giving 1066 MHz in intel speak.

so 266*7 = 1.8 GHz (6300 right?) if using DDR 800 you could get a potential
OC up to 2.8 GHz

[nvening]

Yes, forget the PR and it basically has a 266MHz FSB - Ie for a 1:1 ration you need ddr2 5300

[oralpain]

Yep.

Quad pumped FSB 266*4 = 1066
Dual Channel DDR2 533*2 = 1066

The reason I recommended DDR2 667 or 800 is that the better 975/965 boards and the lower end COre 2s can easily handle 400MHz+ external clock.

[kalniel]

Yes, forget the PR and it basically has a 266MHz FSB - Ie for a 1:1 ration you need ddr2 5300

You mean PC 4200/4300 (DDR2 533).

PC5300 is DDR2 667, which needs to be run at 4:5 ratio CPU:RAM

The actual system speed of c2d desktops is 266mhz. This is quad pumped on the FSB for the CPU, giving the claimed FSB speed of 4x266 = 1066. DDR2 is double data rate ram, so 266 is listed as 2x266=533, hence DDR2 533 for 1:1 ratio. The PC rating is 16x the real speed (for some reason), hence 16x266 = 4256 - this is rounded down to 4200 or up to 4300.

Quad pumped FSB 266*4 = 1066
Dual Channel DDR2 533*2 = 1066

Not quite. Dual channel has no effect on the speed of memory, just it's bandwidth. The relationship is that quad fsb 1066/4 = 266 and DDR 533/2 = 266, hence 1:1.


People recommend DDR2 667 not because of the overclock, but because you can run the memory asynchronously with the CPU, using a 4:5 ratio and that does actually create an improvement in synthetic benchmarks with the c2d.

[oralpain]

I'm well aware that neither dual channel, nor double data rate have any effect on the actual clock frequency of the memory.

I recommended DDR 667+ because of the overclock potential, as I probably would not run a 4:5 ratio, due to the extremely meager performance improvements in any real world task, when a good c2d motherbaord could max out many chips and memory 1:1.

[KingJimi]

Oooh, I feel kinda scared getting some quality RAM - shouldn't it be all standardised? I overclock generously, and I always like a bit of headroom... Corsair just make a DDR 2 Xpert please!!!