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 :D

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!
30 answers Last reply
More about which memory 1333 1333
  1. Lot's of readers of this post but no answers? I'm shocked! :) Surely somebody has some advice.
    ..... please? :)
  2. 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!
  3. thanks for the feedback. Just out of curiosity, what would happen if I used DDR2 1066? How would that affect things? I had somebody tell me I would still be better off with DDR2 1066
  4. 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.
  5. I've been to afraid to ever try overclocking anything ;)
  6. 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 :/
  7. ganthetb said:
    thanks for the feedback. Just out of curiosity, what would happen if I used DDR2 1066? How would that affect things? I had somebody tell me I would still be better off with DDR2 1066



    no dought 1066 mem is fast! but check your mobo as some mid-range boards (like mine if you check my system config) will only take a max of 2gigs of the stuff and not 4 or 8 gigs, but thats if you're on vista 64bit.

    but in all honesty with the pricing of ddr2 800 you can't beat that price per performance ratio!
  8. 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
  9. ganthetb said:
    I've been to afraid to ever try overclocking anything ;)
    those new CPUs are so easy to overclock moderately, just increase the FSB to 400, and very likely it will run just fine at stock voltage. you'll also get a nice match with the DDR2-800 :)
  10. ganthetb said:
    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
  11. @ kari indeed, my Q6600 is running @ 3,2 ghz 400x 8 multiplier. at 1,32V = core voltage. stable. Just a tad warm. But hey, an aftermarket cooler and your all set.

    + you get a very nice performance boost.
  12. 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?
  13. dude trust us on this one! go with ddr2 800 (and get 8 gigs of the stuff) and you will be plenty happy. pending on the brand 8gigs will run ya well under $200.

    trust me! you will be happy. and especially vista 64bit!
  14. radium69 said:
    @ kari indeed, my Q6600 is running @ 3,2 ghz 400x 8 multiplier. at 1,32V = core voltage. stable. Just a tad warm. But hey, an aftermarket cooler and your all set.

    + you get a very nice performance boost.
    yeah, I'm running e6550 @ 3,15GHz, 450*7, 1,375V set in bios but cpu-z measures only 1,28V under load
  15. well I would rather get the DDR2-800 cause it's that much cheaper
  16. Kari said:
    those new CPUs are so easy to overclock moderately, just increase the FSB to 400, and very likely it will run just fine at stock voltage. you'll also get a nice match with the DDR2-800 :)


    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 :)
  17. ganthetb said:
    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 :)
    all those adjustments are done in BIOS, but basically thats all you need to do. You'll better actually set the CPU voltage at some specific value (like 1,3V edit: ooops sorry that voltage is for older 65nm CPUs, those new 45nm need a lot less)) rather than leaving it on AUTO cause that will likely use unnecessary high voltages if left on its own... but read the stickyes on the overclocking section
  18. 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.
  19. The speed your ram is running at is determined by FSB.
    If your FSB is 400 and the multiplier is 8 the CPU is running at 3200mhz.
    If you used 800 memory at 1:1 ratio your memory would be running at 800. DDR is dual data rate and its speed is determined by FSB. The math is 2x400=800 again, providing the ratio is set at 1:1
    Look at Kari's numbers. 450x7=3150mhz
    If Kari is runnng 800 memory at 1:1 ratio 2x450=900 So the ram would be overclocked. That is just an example because at this point we don't know what Keri has the memory ratio set at.
  20. well....I'm more confused than ever now :heink:
  21. The Q9300 uses a 7.5 multiplier.
    so at 2500 mhz the front side bus (FSB) would be set at 333.
    333 x 7.5= 2497mhz
    at 1:1 the ram would be running at, I dont like this number, 666.
    667 memory would work out fine but not much room if you ever want to overclock.
    My choice would be 800 memory to leave room for a little overclock and 800 memory is very affordable.
  22. 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. :bounce:
  23. ganthetb said:
    well....I'm more confused than ever now :heink:

    the math is quite simple really..
    FSB frequency is the base frequency everything else uses as reference.
    DDR memory uses a multiplier of 2, ie if FSB is 333 memory speed is 667.
    CPU multiplier depends on the processor model, Q9300 has 7.5 mine e6550 has 7 and q6600 has 9.
    The quadpumped processor FSB of 1333 only tells that it is meant to be used with FSB 333.
    There is memory divider (FSB/memory ratio) as well if you want to run your memory faster than what the fsb alone would set it at. 1:1 ratio is the most 'stable', but for example 5:6 ratio would result in memory speed of 800 with FSB 333 (thats 333*6/5*2=800) .
  24. 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.
  25. Get the 800MHz ram. It is dirt cheap right now. Just a few days ago they had 2 Gigs of decent Corsair ram (at cas 4) for <$30!!!! I just bought some for my new system although it could take the 1066 (but that seemed like a waste).
  26. jeremyrailton said:
    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?
  27. ^667 in 1:1
  28. jeremyrailton said:
    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.



    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/Product.aspx?Item=N82E16820146731

    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.
  29. Thanks for all the replies gang!

    So check it out. I took a good look at the memory I currently have in my system. It turns out I have 4 gigs of DDR2 667 memory so I guess I should just buy the new MOBO and CPU and use this memory for now. Here are the specs on my memory. Tell me what you think about this plan.

    PC2-5300 (667MHz) 4-4-4-12 1.8V
  30. you'll be just fine with those sticks, and you can bumb up the voltage when overclocking if necessary to gain some more speed
Ask a new question

Read More

Memory CPUs Product