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Can I change my CPU clock multiplier to make my RAM 1:1 ???

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September 15, 2006 1:44:51 PM

So here is my question:

I am running DDR 800Mhz (ie. 400 Mhz) at 4-4-4-15, CAS 4 at 2.0V. My CPU clock is set to 267Mhz by default. People here have said I need to get it to a 1:1 ratio or best performance, so I need to raise my CPU clock to 400 Mhz to achieve that.

If I raise it to 400Mhz, my CPU speed will become 3.6Ghz (I currently have a 9X multiplier set as default on my mobo). SO, if I change that multiplier to 6X, I will be able to achieve my 2.4 Ghz stock speed on my CPU, as well as get the 1:1 RAM to CPU clock ratio.

Will this work? Whats the catch? What are the advantages and disadvantages?

THANKS!!!! :lol: 
September 15, 2006 2:33:43 PM

Quote:


Will this work?


No....

A 1600MHz FSB is way over spec

Anyway the 4MB cache conroe's are not really dependent on memory speed for performance, so even if you could get 1600MHz FSB I don't think you would see much performance change...
September 15, 2006 3:00:21 PM

How do I interpret the FSB? How does this differ from the CPU clock. What must I try set it to? Any ratio considerations with the RAM?

Thanks!
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September 15, 2006 3:06:49 PM

I've figured out that the CPU clock X 4 = FSB? Is this right???

Therefore, a CPU clock of 400 Mhz = a FSB of 1600MHz right?

What should I try get the FSB to ????? It's weird cause it creates a loop/catch 22 situation. If I cant raise the CPU clock to 400 MHZ, I will have to bring down the memory speed right
September 15, 2006 3:07:25 PM

That would also mean a waste of money to buy DDR2 800Mhz if no one can use it!
September 15, 2006 3:31:04 PM

Quote:
That would also mean a waste of money to buy DDR2 800Mhz if no one can use it!


It's a waste for people wit h Conroes, AMD users with X2's can get the full benefit of 800 RAM
September 15, 2006 3:49:12 PM

This is kinda confusing.

Might want to look at your Memory Frequecy settings, I believe that is what effects the ratio.

I'm not on a Conroe system, but my P4 setting may help you understand what I'm saying.

For example on my system, just adjusting the FSB doesn't affect the ratio. I can set the FSB from my default 133 to 148. That would make my P4 2.66 ghz (x20 mulitplier) to 2.960ghz but the ratio will still be set at 4:5 with reg DDR400.

When my Memory Frequecy is set to auto, the ratio is at 4:5, when I set it to the next setting, 266mhz, the ratio is changed to 1:1 on my system since the CPU FSB speed is 533. The 266 setting will change as you up the CPU FSB speed.

Hope that wasn't too confusing to understand.
September 15, 2006 4:53:02 PM

Just to clarify…

CPU clock is the frequency at which your processor works. Just that. In your case: 2.4 GHz.

Current FSB for C2D (assuming it could change in the future, I don’t know) is quad pumped. This means 4x 266 MHz = 1066 MHz.

As you already know there’s the multiplier, which is (in a simple way) a value that allows processors to work at a much higher frequency than that of the motherboard.

There is also a multiplier working on your system RAM in the same fashion.

By means of the multipliers, you can tweak the frequencies of your motherboard, processor and memory.


Now… It has been reported that C2D’s benefit little from going beyond a 1:1 ratio (currently, memories faster than DDR2 533).

For what I understood, your are just interested in having a 1:1 ratio between memory and motherboard, and not particularly in over-clocking your CPU.

That said. You are NOT loosing anything by not having a 1:1 memory ratio. You do benefit from the extra 133 MHz of your DDR2 800. Not by much but you do.

Although possible, raising your FSB to 1600 MHz is quite extreme. And since C2D’s are not bandwidth constrained, I doubt you would see any noticeable gains by doing it (even if it does provide you a 1:1 memory ratio).
September 15, 2006 7:48:20 PM

Hi BMFM,

That makes sense. How do you know all this stuff? I guess my question to you would be - how exactly do I optimize my system here? What are my options. I'm looking into getting a Scythe Ninja Plus next week and am going to take the OC jump.

I dont know anything about this so I sont know if 1:1 is better than having higher memory speeds with 1.5 ratios (like my current setup) etc. Shall I just max out my memory speed until it crashes and set it back a few Mhz.

I'm running DDR 800 at 400Mhz, at CAS 4, 4-4-4-15 timings at 2.0V. I could increase the voltage to 2.2 without voiding the warranty, and maybe even get higher memory speeds. What do you think about this. Should I relax the timings somewhat (maybe to 5-5-5-15), and get another 133Mhz out of my RAM?

What are all my options here? I just wanna get as most out of the system as I can (bang for my buck). At the same time, I really like learning about computers. THANKS! :lol: 
September 16, 2006 1:06:46 AM

What I wrote you is pretty basic, general stuff, that you get here and there (mostly reviews and news). I confess that if you asked me for detailed technical info I would have a hard time… I mostly like to read about the practical stuff, not the heavy technical. No mystery there.


I believe you would actually loose performance from down-clocking your memory (even with tighter timings), but in the end, I guess you could give it a try and check it out first-hand.

About your queries on over-clocking, I’m afraid I’m not the best to coach you on how to do it as I’ve never done it myself. You will probably get the info you need on the over-clocking section of the forum.

Regards.
September 16, 2006 2:09:05 AM

Quote:
So here is my question:

I am running DDR 800Mhz (ie. 400 Mhz) at 4-4-4-15, CAS 4 at 2.0V. My CPU clock is set to 267Mhz by default. People here have said I need to get it to a 1:1 ratio or best performance, so I need to raise my CPU clock to 400 Mhz to achieve that.

If I raise it to 400Mhz, my CPU speed will become 3.6Ghz (I currently have a 9X multiplier set as default on my mobo). SO, if I change that multiplier to 6X, I will be able to achieve my 2.4 Ghz stock speed on my CPU, as well as get the 1:1 RAM to CPU clock ratio.

Will this work? Whats the catch? What are the advantages and disadvantages?

THANKS!!!! :lol: 


1:1 is a 200Mhz FSB in your case.
September 16, 2006 2:13:29 AM

The timing issue is a funny one. If you ram is twice as fast but takes twice as may cycles to transmit the data there isn't any real benefit. This is why there is very little difference between the performance of DDR and DDR2. Bus bandwidth was the problem with Rambus.

Another way to look at it is to think of a road. If you need to move more people down the road in the same amount of time how do you do it? One way is to increase the speed of the cars (MHZ). Another is to make the cars travel closer (timings). A third way is to increase the number of lanes (bandwidth).

The last way is one of the best but it is costly and requires significant changes to both the road and ram. The other two though can be done with relative ease but could cause collisions or data errors.

To be honest though most people won't notice a big difference in performance from slightly lower timings or slower ram. +85% of the time your cash will handle the memory needs of the CPU.

For over clocking purposes it is best to first remove ram from the equation. Lower timings and if you can lock the ram speed, do so.
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