FSB, under- and overclocks. Aided Education Please

[MOUSY]

First off, apologies for the long post. I'm trying to educate myself.

OK. Let's see if my research has enabled me to get this right. Please tell me if I have the general idea on how this works.
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1)
The FSB on DDR2 800 is 800/2=400
The FSB on a Q6600 is 1066/4=266.5
And the multiplier is locked at 9, giving you 9*266.5=2398.5 (Stock speed of about 2.4Ghz)
Hence, the mobo would automatically underclock your memory to get them to run in a 1:1 ratio? Is that right?
Would that mean then, that all one would really need is (266.5*2=533) DDR2 533 memory?

2)
In order to get a lesser underclock on your DDR2 800 memory, one could run your Q6600 instead at an FSB of 1333.
That would get you 1333/4=333.25
Hence this time one would only (need 333.25*2=666.5) DDR2 667. Right?
And a resulting overclock of 9*333.25=2999.25 (Just under 3Ghz 8-))

3)
In order to attain a 1:1 ratio between DDR2 800 and your Q6600 and not underclock your memory at all:
One would need a mobo FSB of 400*4=1600 (Searched for Mobo's with such FSB's... no luck)
Resulting in a net overclock of 9*400=3600 (3.6Ghz )

Did I get that all right? Is that how things work?
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Now for a few more questions
1) Can the Q6600 handle 3.6 even under an after market air cooler like the Zalman 9700? Would you all even recommend pushing that far? I've read that a few people have done it on air. But looks to me that the life of that processor is down to 2 years or less.

2) Are the CPU and memory FSB's completely separate? Can they be set unlinked so that they run in a 2:3 ratio instead, for example, to prevent a memory underclock but without overclocking your CPU?

Thanks in advance to anyone answering my lengthy questions.

[Nick N]

Mouse

I am going to refer you to

[MOUSY]

Hey Nick. What's your handle on that forum? Want a "Referrer" for my registration.

Been skimming about the forums... wow.... waaahaaahaaayy above my level....
I'll have to lurk around for a few weeks before I can hope to get to the levels of the convos up there.

Anywayz, I guess my real question was:
Would I be better of buying cheaper, slower memory like the 667 since all of the 800 won't be used, even on a 1333 CPU FSB?

[Nick N]

Hey Nick. What's your handle on that forum? Want a "Referrer" for my registration.

Been skimming about the forums... wow.... waaahaaahaaayy above my level....
I'll have to lurk around for a few weeks before I can hope to get to the levels of the convos up there.

Anywayz, I guess my real question was:
Would I be better of buying cheaper, slower memory like the 667 since all of the 800 won't be used, even on a 1333 CPU FSB?

I could tell you that, but then I would have to kill you... sorry, I dont give my name out for that forum

They wont let you sign up without a referrer? I have been there for years so I did not know that had started, then again as I recall I had one from a corporate source so perhaps that is required,.. so long ago I dont remember.

Well, I did say to lurk there. I did not expect you to sign up.


As for your question, so what you are telling me is you have no intention of going into your BIOS and setting up the system. thats silly and I cant see how you intend to overclock at all unless you do.

The memory wants to be at least DDR 667 for normal use (no clocks) but to get the memory chatting with the 1333FSB processor directly it needs to be DDR 800, 1000, or 1066 product or better and you need to set it up right in the BIOS.

The faster the memory and the lower its CAS timing the better you will clock


The P5k3 Deluxe P35 DDR3 does 500-520FSB (a bit more on better cooling) if the right PSU and cooling is used, so there you have it

the X38 chipset does better

[MOUSY]

No, a referrer isn't mandatory. Just noticed it and remembered you.

Anyway, I do intend to go into the BIOS to properly set up the system.
Just that, from what I've learnt (or thought i learnt), even changing from 1066 to 1333 FSB on the board won't allow me to make full use of the FSB (400) on DDR2-800 memory, since it would be only 333.25 for the CPU (or maybe I'm dividing wrong and it should be 1333/2=666.5).

Maybe I don't fully understand as yet. Any clarification on that matter would be greatly appreciated.

[Nick N]

You are getting into the dividers and if you wish to run 1:1 with the processor. Those are based on the motherboard and the BIOS programmer

In example, a strap change takes place on the P5K3 Deluxe at 420MHz FSB, meaning the dividers for the memory change. In order to reconfigure so you remain in 1:1 or another divider, you must understand how that individual motherboard is designed to work. That is why I sent you to that forum. You will usually find the better motherboards there discussed and all their little hidden math secrets that are not in the manual

So to run 1:1 on the PK53 Deluxe with very good memory as fast as I could go on todays parts, I would set to 333 CPU Strap (1:1), set the FSB to 500 and the memory to the 1333 scale (that changes in the BIOS based on the strap), and the multipler (that thing you are not paying for and have lots of room to play) so I dont exceed the CPU's ability, that calculates to a memory speed of 1000Mhz, DDR3 2000 on a FSB of 500 with the CPU maintaining its 1333FSB core programmed speed on the strap of 333. If I use a 7x multiplier thats 3.5gig.. bump up to 8x if I kick in phase change cooling.


If you are asking for basic formulas they are all the same as you posted above, but, the difference is new motherboards allow strap locking which changes the divider and how it works. You have to know and research the board/bios to get the most out of it. The basic formulas only work for strait clocks on boards that have no strap setting or other dividers changing dynamically, such as with Black ZR-1 and how I got him through the calcualtions in the FSX forum months ago, it was strait forward





The deal is, the faster the memory, the higher you go, stable. Even if you hit the cap on the CPU, you want the memory to be able to go as fast as you can possibly get it.

But the BIOS has to have all these setting I am discussing available too. You must download the manual, research the board past the manual and learn how it all works

I cant do that for you

Your problem is you wont have the multiplier available and you will only be able to go so far because the only way to clock the processor you selected is to use FSB/strap (if the strap lock is available on your board). Withthe P5k3 Deluxe, the manual does not have the strap setting in it, it was added in a later BIOS release... you have to RESEARCH!  LOL

Since each motherboard has its own BIOS/setting and divider quarks, you have to figure out how high you can go on your processor, then using the math the BIOS allows and any little secrets you can dig up on the net about changes not published in the manual, figure out the best choice for memory.

Since you can only go so high because you can not reduce the multipler, the memory speed will only get you so far. I cant tell you what that limit is, if that is what you are after, unless I personally researched it all out myself. Sorry, i dont have the time

[MOUSY]

Ahh ok. Now I get it. My mistake was thinking it was that straight forward for all boards. Thanks for the clarification Nick. I've been motivated to do that research.

[Nick N]

Ahh ok. Now I get it. My mistake was thinking it was that straight forward for all boards. Thanks for the clarification Nick. I've been motivated to do that research.

Its not as strait forward as it was 10 months ago

the only problem with what you said in the first post is in running 1:1

Running 1:1 requires overclocking, not underclocking

to run 1:1 with a 1333 CPU you must bring the memory up so its divider is on the same scale as the 1333 strap clock

In that case it may be better to drop the strap to 1066 so it is easier to nail the 1:1 ratio on a lower memory clock. At 1333 you will need memory that can push a good boost as in the 665.5 range, thats full MHz speed, not DDR 667 (/2)

So the million dollar question for you is, what FSB/divder will give you that speed and not overrun the max the CPU can do on the locked multiplier


In your case you need to figure the best you are going to do on air, safe and on a 9700 is about 3.3gig.. you may get better or less, I dont know but that is a good number to play with. So now you know the approx max on the CPU, use the locked multiplier WITH the CE1 features disabled (power save) and then figure out the FSB... and then see if the board has a strap change or EVEN a separate divider setting (some do) available.

Once you figure out the max the CPU/FSB will go, you can select the memory.. always select the next level UP in memory, NOT DOWN and especially if you are borderline.

[MOUSY]

Oooohhhh. My mistake was thinking I was to divide by 4 instead of 2 to find the memory clock. Hence to get a 1:1 ratio out of DDR2-800 on a 1066 strap I'd have to push an extra 133Mhz out of it. Allright. This is all getting clearer.

[Nick N]

Oooohhhh. My mistake was thinking I was to divide by 4 instead of 2 to find the memory clock. Hence to get a 1:1 ratio out of DDR2-800 on a 1066 strap I'd have to push an extra 133Mhz out of it. Allright. This is all getting clearer.

You can do that on the divider too depending on how it is set up in the BIOS but now you are seeing why not having DDR3 and a 1333 processor sucks.

In order to run 1:1 you need to be chugging along in memory speed and DDR2 is limited. DDR3 starts at 1066-1333 and goes up from there.


If the motherboard and BIOS supports it, you can run 1:1 on the 800 strap, the 1066 strap or the 1333 strap

I have a board with a 1600 strap here

[MOUSY]

I have a board with a 1600 strap here  ;D

D^mn!