Question about Multiplier on e6600

[Meithan]

Primarily because DDR2 speeds are faster than Intels FSB. On current 965 boards, there are actually NO options below 1:1. That means that the lowest you can run the RAM is equal to the FSB, however, you can run the RAM faster than the FSB.

Are you sure about this? I thought it was the other way around. For instance, 5:4 would mean that the RAM runs at 80% the FSB, 3:2 would have RAM running at 67% the FSB, etc.

 

[idiotec]

Are you sure about this? I thought it was the other way around. For instance, 5:4 would mean that the RAM runs at 80% the FSB, 3:2 would have RAM running at 67% the FSB, etc.

You are correct with that, but what I am saying is that on most newer Intel boards, they do not have downward memory dividers. What you see on these boards is more often the reverse of those dividers (i.e. 4:5 instead of 5:4).

Again, this is do to the current ratio of FSB and DDR2 speeds.

C2D has a FSB of 266. Most people are running DDR2-667 and DDR2-800 on these boards. In order to have the memory run at full speed at stock FSB, the board has "upward memory dividers."

Example: for DDR2-800 to run at full speed at a FSB of 266, it takes a "divider" of 2:3 (not 3:2).

Make sense?

 

[Meithan]

Uhm. It does make sense. If memory ran at 1:1, then DDR2-800 would have to downclock all the way from 400Mhz to 266Mhz to match the FSB. I still don't understand the Gigabyte nomenclature though. The settings 2.00 corresponds to 1:1??

 

[idiotec]

The settings 2.00 corresponds to 1:1??

Yeah. I can't say why they did it that way, but that is how it is shown in the BIOS.

I guess it makes some sense in an "intuitive" sense. You basically just multiply the number by the FSB to get "DDR" RAM speeds.

Example:

2.00x266=DDR2-533
2.00x400=DDR2-800
3.00x266=DDR2-800

 

[Meithan]

Yes, it sounds possible. I guess they just wanted to match "advertised" DDR2 speeds to avoid confusion. Not a smart move since the people messing with BIOS settings work with the actual RAM speeds. I still call it DDR2-800, but I know it runs at 400Mhz.

 

[Max2559]

Ok im confused...

I will tell you what i did and what cpuz reports... you tell me how the ratios explain it... (id appreciate the help getting my head around this one once and for all!)

In bios

Set FSB to 266. (RAM is currently set to AUTO)
Notice that RAM speed is at 667 (So want to change a setting there to get it to 800Mhz)
Change it from auto to 3.00 and get the 798Mhz displayed.

Boot up... CPUz reports FSB at 266 and ram at 400 Mhz. (That sounds Ok .... as was mentioned by Meithan DDR2 is ment to run at 400Mhz... but in dual mode i think this does tally with 800Mhz? ?

Just as a reference Easy tuner5 reports RAM at 798 here... it seems CPUz reports the single DDR speed... and my bios and easytuner report the dual ? ?

Im pretty sure it right but clarification would be much appreciated. Dont be too hard on me ive only been learning about a month!

 

[Meithan]

It all works out, Max2559.
When in AUTO, the BIOS set the FSB:RAM ratio to 4:5, or 2.50 in your BIOS (ie, RAM speed 1.25x FSB speed), giving 333Mhz (667Mhz effective).
When you changed to 3.00, the ratio became 2:3 (ie, RAM speed 1.5x FSB speed), thus giving 400Mhz (800Mhz effective).

As for the dual channel mode, it doesn't have any impact whatsoever on the reported RAM speeds. CPU-Z is reporting actual DDR2 speed (400Mhz) while your BIOS and Easy Tuner5 are reporting effective DDR2 speed (~800Mhz).

Did it make any sense?

 

[Max2559]

Yes... i totally understand now.

Cheers Meithan.

Currently i have FSB at 367. . . (multiplier of 9)
RAM divider at 1:1 (or on my board it just says 2.0 as you know)

So RAM is actually running at 367 ... but My bios reports the effective DDR2 speed of 734.

Gottcha!

 

[Meithan]

We all learned something today .

Also, FSB at 367Mhz... nice... On what motherboard did you achieve this?

 

[TheMajor]

EasyTune5 and Sandra are broken. CPU-Z reports the actual clockspeed.

If you think Sandra is broken, then you are probably looking at the wrong module.