The Effect of Multipliers

[Exile69]

I was recently reading a couple of reviews where the reviewer in one instance brought his 2.4Ghz AMD processor from 200x12 to 300x8. In another instance the reviewer brought his CPU from 200x14 to 400x7. I was wondering if or how much of a positive effect this would have. And, as an example, is a 3500+ Venice @ 2.2Ghz stock equal to, better, or worse than a 3000+ Venice running @ 2.2Ghz in the exact same configuration? Let's just say these two processors were made on the same day. Also, when they say 2000Mhz HTT, I'm under the impression that this is representing the FSB, at stock it would be 200 with an LDT multiplier of 5 at full duplex yeilding 2000Mhz HTT. Is that right?

[GrahamGarside]

The only benefits to reducing the multiplier and going for a higher clock are firstly to get the optimal clock speed setting whilest keeping the memory at DDR400 using the correct divider, or to get the memory at it's highest capable speed if you have premium ram like TCCD, UTT or BH5 etc..

[Exile69]

Are you putting any stress on the CPU by bringing it from 14x200 to 400x7?

[GrahamGarside]

I don't think so. But there are no ram modules that can take that speed so there are no benefits in attempting it and I doubt any board could manage it without extreme cooling.

[Exile69]

Originally Posted by Me

And, as an example, is a 3500+ Venice @ 2.2Ghz stock equal to, better, or worse than a 3000+ Venice running @ 2.2Ghz in the exact same configuration? Let's just say these two processors were made on the same day.

What about that?

[GrahamGarside]

An athlon 64 core running at a given clockspeed performs the same regardless of it's stock speed as long as all things are equal.
Even if there is an increase in HT bandwidth, this bus can carry so much data anyway that it has no impact on performance.

Like I said, the only reason to lower the multiplyer to raise the HTT clock is to get a faster memory clock or to hit a sweet spot for keeping the memory at 400mhz

[Exile69]

When you say all things are equal, what do you mean by that? The 3500+ would be running at 200x11 and the 3000+ would be running @ ~245x9. That seems quite different to me. Would these two have equal performance? I'm guessing yes.

[GrahamGarside]

All things being equal as in the rest of the system is the same spec and the memory clock is the same, which 9x245 wouldn't be, as there is no way to get the memory to run at DDR400 with that clock, you need to run at 250/266/300 HTT clocks to then get a 400mhz memory clock which you can only achieve 2.25ghz from, giving the overclocked 3000+ a slight performance lead over the 3500+ but only by an amount equal to the cpu clock speed advantage