Intel memory requirements.

[SouthernShawz]

I am going get an E6600 CPU and a 1066mhz compatible Asus P5N32-E Motherboard. Do I need 1066mhz memory? it seems lots more expensive than 800mhz...

[Thermo]

Dual-channel DDR2 800/667/533 is the memory that board supports.

AFAIK the only 1066 memory is still RDram. Oh how sweet it was back in the day

[Buckeye Kid]

I am going get an E6600 CPU and a 1066mhz compatible Asus P5N32-E Motherboard. Do I need 1066mhz memory? it seems lots more expensive than 800mhz...

No, the minimum memory required to run that processor is 533mhz. Anything higher is good for overclocking, but if you are asking this question I don't think you are looking to overclock :P

DDR2 memory is always 1/2 of the FSB rating. So if your FSB is 1066 (like the current e6600) you need half that, or 533. In the future, Intel will run processors at 1333 FSB, so DDR2 667 will be the miniumum required.

Just as an FYI, when you overclock you increase the FSB rating up from stock. So for example, if I have your motherboard and processor and I want to overclock the processor I may increase the FSB from 1066 to say 1250. Well, when I do that I would then need memory rated at 1250/2 = 625mhz. This means one of 2 things, either I need 533mhz memory that will overclock up to 625 mhz OR I need to buy DDR2 667 (the motherboard will automatically run higher speed memory at the required speed as determined by the motherboard FSB).

Memory doesn't overclock as well as motherboards, so people usually buy memory that is slightly higher rated in speed than thier motherboard. So if you have that motherboard you were looking at the MINIMUM memory is 533, for a light overclock you would buy 667 memory, for a mid range overclock you would buy DDR2 800, and if you wanted to overclock your computer 100% you may buy DDR2 1066.

These are the BASICS of course, there are a lot of things that can affect all of what I just said, but that is the basics of memory and how it relates to overclocking explained :P

[Un4given]

I should probably make a sticky on this, since this question has been asked at least 6 times in the last few weeks.

The Intel uses a quad pumped FSB; it's actually 2 x DDR busses running 90 degrees out of sync. As a result of that, whatever the FSB is rated at, you simply divide that number by 4 to determine the true, non-DDR, clock speed. So what you end up with is a true clock speed of 266MHz. Since it is a DDR bus that makes it 533MHz. Since there are two of them, you now have 1066MHz. The fact of the matter is that nothing about FSB and RAM requirements have changed with the C2D, and are exactly the same as the P4.

To have a 1:1 match for a 1066MHz FSB you need DDR2-533MHz (PC2-4200). Since the memory is dual channel, with two sticks you get your matching 1066MHz.

When the FSB moves to 1333MHz you will then want to use DDR2-667MHz (PC2-5300).

Actual FSB Clock              Rated FSB Clock                 Min. RAM Needed
    100MHz                      400MHz                         DDR PC1600                   
    133MHz                      533MHz                         DDR PC2100
    200MHz                      800MHz                         DDR PC3200
    266MHz                      1066MHz                       DDR2 PC2-4200
    333MHz                      1333MHz                       DDR2 PC2-5300

* Intel skipped from 133MHz to 200MHz, so a 166MHz FSB was never implemented. If it had been, DDR PC2700 would have been used. A 1600MHz bus has not yet been implemented, but if/when it is, DDR2 PC2-6400 would be required.

** The above values are based on running a 1:1 syncronous RAM/FSB. It is possible to use RAM that is faster/slower using the memory dividers to run the RAM/FSB in asyncronous mode.

[Nater]

I have DDR2-1066, but I run it down at 800MHz @ CL3. That's another good use of fast memory, you can always clock it lower and tighten the timings.

[ua549]

Pc2-5300 memory came on my Dell Latitude D620 notebooks (Core2 Duo T7200).
The bus speed is 166+MHz yielding a rated FSB of 666MHz.

[Un4given]

Pc2-5300 memory came on my Dell Latitude D620 notebooks (Core2 Duo T7200).
The bus speed is 166+MHz yielding a rated FSB of 666MHz.

Oh cool. I wasn't aware Intel had used that bus speed at all.

[ua549]

The probably did it to save power.

[proxops-pete]

Pc2-5300 memory came on my Dell Latitude D620 notebooks (Core2 Duo T7200).
The bus speed is 166+MHz yielding a rated FSB of 666MHz.

Ah... the show of the devil!!

[dolphin]

To have a 1:1 match for a 1066MHz FSB you need DDR2-533MHz (PC2-4200). Since the memory is dual channel, with two sticks you get your matching 1066MHz.

What if it is single channel? You only get 533mhz?

[schoolreallysuxs]

seeing the price of ram, i would just get ddr2 PC 6400 and run it slower as needed/tighten timings. if you decide to OC later, all the better!

[Nasty]

Oh cool. I wasn't aware Intel had used that bus speed at all.

Yep, it's true. I knew that Intel used a 166MHz (actual clock speed) FSB (667MHz quad-pumped) for its mobile processors. The key is that Intel never used that particular FSB speed for its desktop processors.

[fist]

hmm

As I understand, using 4 memory dimms in Xeons mobos chipset 5000 and above will enable quad channel memory..

does it mean that for example FB-DDR2 800 will support 3200 FSB ?

I understand that in the Xeon 5400 chipset you must populate ram in pairs (to reach new fsb 1600 ) but also if you use 4 , 4 channel will open.. I wonder how this would affect OCing a Xeons using 4 channels... the problem is each channel will still OC with the cpu fsb ... regardless of the use of 2 channels or 4 .. so if the bios can set the fsb of memory 1/2 or 1/4 of CPU in case of 4 channel we will have an OC monster..

since the cpu now runs at 1600FSB (4x400) , using quad channel DDR2 needs only to be 200 FSB DDR2 (200x2(ddr)x4(chanels)) so we have the freedom of +200FSB to raise for a XEON CPU , we can OC the cpu with 600FSB using fb-DDR2-800 in case memory fsb is 1/2 cpu fsb

anyone comments?

[je_dryst03]

How do i find out my CPU model?

[Soul Assassin]

Why is this a sticky thread?