Which memory for 1333 FSB and 1333 CPU?

Hi all,
I have been building my own PCs for a while now but I'll admit to being novice about several things. In particular I am not clear on matching memory speed with the motherboard and cpu. I am not interested in overclocking, so this should be pretty simple (I hope) for one of you gurus to answer

I am going to use the Intel Core 2 Quad Q9300 Yorkfield 2.5GHz CPU which can run at 1333 MHz and for motherboard GIGABYTE GA-P35-DS4 which also runs at 1333Mhz FSB. This board can take DDR2 1066/800/667 memory.

If I have read correctly, it's better to use DDR2 667 (instead of DDR2 1066) because the math somehow works out to equal 1333. I really don't quite get how that works but in any case, I really just want to know what memory I should use when the CPU and MB are running at 1333 Mhz

Any help? Thanks!

you got it right! ddr2 667 mem (remember it's dual channel) is equal to a proc with 1333FSB. so buying ddr2 667 mem will put you 1:1 ratio with 1333FSB without having to overclock!

also what is better used is in the eye of the beholder! for instance: i have the e6550 1333FSB proc with ddr2 800 mem. to bring it 1:1 i only overclocked the proc from 333 clock (in the bios) to 400 thus riasing my FSB to 1600 from 1333.

well the base freq is 333MHz, but since Intel 'quadpumps' it for the CPU it becomes 1333MHz. That 333 also means you'll need DDR2-667 (or faster) to run with 1:1 ratio, dual data rate memory (DDR) in dualchannel mode so basically 333*2*2 and you'll get a match.

But DDR2-800 is so dirt cheap nowadays, it's better to get that instead. You can likely tighten the latency timings a bit with the 800 as well when running it at 667.
Running the memory faster than the 1:1 ratio yields only small improvments and usually isn't worth it, ie buying DDR2-1066 which costs a lot more isn't usefull

edit: wow 5 replies when I was writing mine, lol I'm so slow

Hmmm...so if I used DDR2 1066 (my MB supports it up to 8 gigs) would there be any negative impact on the overall performance of the system? Somebody else told me if I used 1066 that my FSB and CPU would scale back to 1066 instead of 1333. That didnt sound right

thats BS, you'll get slightly increased performance with faster running memory

Thanks Kari,
OK to sum it up for the remedial (that would be me), I should just get DDR2 1066 memory. That will give me slightly better performance than DDR2 667?

yeah, I'm running e6550 @ 3,15GHz, 450*7, 1,375V set in bios but cpu-z measures only 1,28V under load

So I would get DDR2 800, I would adjust the FSB to 400 (I assume that's up from 333). Do I have to adjust something to the CPU as well? I've never attempted any sort of OC before

I would go with the 800 and bump the the FSB in Bios to 400. Most likely it wont need any other adjustments for voltage ect.. Set the FSB to 400 save and it will reboot. If it posts which it should then load windows and monitor your temps for a while with Coretemp. If it gets over 70C get a better cooler or give it less voltage. Drop the voltage until you cant post anymore then bring it up a notch.

If it dont post which I doubt a 400 then you need a slight increase in volts.

It should work perfect without any hastle though. If it does then you will have you CPU running at 3.0 just like a stock q9450 for alot less money.

Running 1:1 ratio is a perfect match. If you run 1066 memory you'll run like 2:5 for example theres different ratios involved. At 1:1 every clock your CPU runs will run the same on the ram. On 1066 your Ram will run 5 ticks for every 2 ticks of CPU.

Im running 800 ram and its only running 720 at a 5:6 ratio. My CPU e2180 has a 800FSB which I overclocked to 1200FSB. I cant get this puny CPU up to the require 400 to run 1:1, but if I had 667 memory i could run 1:1 at 333. Hope this helps its kinda confusing.

Long story short 1066 would be a waste of money IMO.

well....I'm more confused than ever now

yeah I'm using 1:1 ratio allright, the funny thing is I'm using DDR2-675 corsair memorysticks so it's overclocked quite much, and only 2,1 volts with 5-5-5-15 timings.

dude, long story short, just get some really good DDR2 800 memory, like crucial ballistix. That is the best performance at the best price point. Your mobo will adjust memory speed to match your fsb. If you learn how to overclock and want to try it out, this memory will overclock along with you up to and exceeding 1066. That's all 1066 memory is, anyway, overclocked 800 that they jack the price up on.

So if I get DDR2 800 what speed will my 1333 FSB motherboard scale it up to?

Crucial changed the chips in the Ballistix, I just bought a set and they are no longer Micron D9 they are some other single sided chips which are no where near as good.

This would be my suggestion
http://www.newegg.com/Product/Prod [...] 6820146731

The DDR2 standard is 1.8v which means that all these other sticks which advertize 1.9 or 2.0 or whatever are being sold at their overclocked speed. These are sold at 5-4-4-12 1.8v which means it's actually DDR2 800 not something else trying to be.

you'll be just fine with those sticks, and you can bumb up the voltage when overclocking if necessary to gain some more speed