# Help needed calculating memory speed

Discussion in 'Motherboards & Memory' started by Lazzer408, Feb 1, 2007.

1. ### Lazzer408

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I need some help understanding exactly how Intel (maybe others) figure out the memory speed. I have 2 options effecting the memory speed (mhz). They are...
Memory speed:
400
533
667
800
Reference frequency:
133
200
266
333

What does all this mean? Can it be translated into ratios? For example would memory speed 400 and reference frequency 200 mean 1:2? Is it as simple as dividing Memory speed by Reference frequency to get the ratio? 400/200=2 or 1:2? Would 800/333= 1:2.4? Sounds wrong that way. I just need to know what my ram will run at with each combination. It's alot easier when I can just flat out choose a ratio. Can someone spell it all out for me? Thanks.

2. ### Lazzer408

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Bump. Anyone understand this?

3. ### Athlon2K15HyperVtX™

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reference frequency looks like it is the FSB of the cpu and memory well thats just the memory speed

4. ### Lazzer408

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With Ref at default and mem at 400 the mem runs 571 and fsb is 383 actual speeds

5. ### francis511

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double the number on the bottom to get the ddr2 freak on the top (i think)

6. ### DanTheBanjomanSeñor Moderator

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DDR means double data rate, this effectively doubles the clock. So for example 266MHz DDR has a reference of 133MHz. And 800MHZ DDR has 400. Intels FSB is quad pumped as they call it. This means an 800MHz FSB actually is a 200MHz FSB. 1066MHz is 266MHz. To get the exact memory bandwidth to match the FSB you need dual channel of whatever the FSB runs at. So a Conroe with 1066MHz FSB requires (well, recommends)dual channels DDR533. If you have faster memory you can voerclock your processors more easily without using memory dividers.

7. ### Lazzer408

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That doesnt explain what the reference frequency is. Default ref is 266 on my CPU. I can set it to 133, 200, 266, 333. What effect does this have on the system? I think this is the NB strap.

8. ### DanTheBanjomanSeñor Moderator

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Reference should be the actual clock.

9. ### Lazzer408

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Clock of what? I can set my fsb clock in 1mhz steps up to 499mhz. The memory frequency I can set to 400, (533), 667, and 800 but as an example... with the fsb at 389 the mem is 779 though it's set to 533.

See if this math makes sence to you. Given all settings defaulted on a 6600 (266fsb) using 533mhz memory. The default Ref is 266, mem at 533.
If I bump the fsb to 389 then mem winds up at 779. If I take mem setting (533) divided by ref setting (266) I get 2. 380x2=778 So somehow the ref and mem = memory ratio. Using that math if I set ref to 333 and mem to 800 I think my memory would wind up at 934mhz 800/333=2.4 2.4*389=934 but I don't know.
numbers numbers numbers

10. ### DOM

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im lost now , so what do you want your cpu at? and where do you want your mem ??

cuz on my mobo in specs. if you have the cpu at 400X8=3.2GHz and mem at 400X2=800Mhz it would be 1:1

is that what your trying to find out ??

cuz right now i have it at 470X8=3760Ghz and mem at 587.5X2=1175Mhz at 4:5

11. ### Lazzer408

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Does this help? This is where I'm at. I'm trying to get my memory to go faster. It's 800mhz 4-4-4-12 @2v but I cant even get it to run 780 4-4-4-12 at 2.35v. I tried cranking up the fsb and nb voltage to the max and still no stable memory at 4-4-4-12. That's my only issue now. Currently my memory is set to 533 5-5-5-15 at 2v to be stable.

12. ### DOM

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you mean 780X2 or 390X2=780

why dont you oc it in the bois its alot better

13. ### Lazzer408

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My front side bus is set at 389 to equal 779 on the memory. I do most of the settings from the bios but this is handy for bumping up the bus while prime is rinning to find instabilities.

14. ### DOM

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okay so have you tryed setting it in the bois 400X9 on the cpu and mem at 400x2 on the ram see if its boots cuz i set mine at 1.55v on the cpu to get it stable at 3.6GHz

15. ### Lazzer408

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I havent tried setting the CPU that high. It's pretty damn hot 66c full load when it's at 3.5. Like I said my memory won't do what it's rated to do. it's 800 4-4-4-12 2v memory. Why can't it do 4-4-4-12 at 779mhz even if I turn the mem voltage up to 2.35? I thought it might have to do with that NB strap thingy.

I can't set the memory to 400x2. I don't have that option. I think I would have to set the memory to 400 if I set the fsb to 400 but if it's x2 or x1.5 or x1.33 or whatever...I have no way of knowing

16. ### DOM

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oh, cuz can you run the cpu at stock and mem at stock 800mhz in the bois ?

17. ### DOM

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lol, well mine shows, say i put the cpu at 400 the mem shows 800 in the bois so i dont know how your mobo is sorry about the 400X2

Last edited: Feb 3, 2007
18. ### Lazzer408

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With the cpu set at default, ref freq set to default, memory set to 800, timing set to 4-4-4-12, and mem voltage set to 2v (per manufacture recomendation) it doesn't post. At 2.35v it boots but I have all kinds of problems in windows. When I boot into windows it says the registry has been recovered from a backup and I only have 36 processes running instead of 38 and CCC doesn't load. When I set the memory to run at 667 4-4-4-12 it's fine but I still need to raise the mem voltage to 2.35v. Maybe this is just shitty memory. There's another \$320 out the window. I hate compatability problems with every single piece of hardware I buy.

19. ### DOM

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can you rma the ram ?? cuz it seems its got a bum leg

\$320 i payed less for mine

20. ### Lazzer408

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http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=2176263&CatId=2367

I have 2 sets of these. I see they have there 2gb kit (1gbx2) for \$270. I wonder if they would allow an exchange of these.

Are 2x 1gb modules more stable then 4x 512gb modules?

I tried switching and swaping these around to no avail. Maybe it's a bad run?

21. ### DOM

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have you tryed just one set? how long have you had them? i dont think they would do exchanges but i dont but from them

cut if you go vista it would be better with 1gbx2 cuz you can add another 1gbx2

22. ### Lazzer408

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