multiplier, fsb, and temps

[Kewl Munky]

My friend is telling me that with a CPU a higher multiplier means you can have a lower FSB, and a lower FSB produces lower temperatures.

If it's true or not, could I have an explanation of how it works which ever way it does to get an understanding?

 

[James^.^]

Hehe, That stuff confuses that ShI- crap out of me. I could benefit from what anyone says here. Post a link if anyone finds something on it.

 

[TrainTrackHack]

The CPU speed is "System Bus" x "Multiplier". The FSB speed is directly tied to the System Bus speed in case of Intel CPUs. So, the higher the multiplier, the lower you can run your FSB to reach a certain CPU clockspeed, so high multipliers are desired when OCing but if you don't plan on OCing the multiplier doesn't matter, as the FSB will automatically run at the default specified by the CPU.

 

[vix]

FSB speed is the key to overclocking. Yes, sometimes you need to add additional voltage to get you CPU stable at a higher speed, but I'd much rather use a lower multiplier and a higher FSB for better overall performance.

example: 8 x 500 FSB gives me better results than 9 x 445 FSB.

The faster the CPU runs, the more voltage needed, and since additional voltage generates heat, your temperatures rise. Key to overclocking is either investing in a good cooling solution, or finding a sweet spot somewhere between performance and acceptable heat levels.

 

[TrainTrackHack]

but I'd much rather use a lower multiplier and a higher FSB for better overall performance.

example: 8 x 500 FSB gives me better results than 9 x 445 FSB.

To this, I'd like to add that this is because all data being suffled back-and-forth between the CPU, memory, and other components have to go thru FSB at some stage, and higher FSB means more throughput.

 

[Kewl Munky]

I read through some of that Overlocking 101 thread and I read that one part where they downed the multiplier and got a better OC, but my main question is is does a low multiplier necessarily mean a higher fsb, and does a higher fsb necessarily mean a higher temperature?

Also, does anyone have any recommendations on a good OC setup for a Q6600 on an evga 780i motherboard? I was thinking of going to like 3ghz, but haven't done a stress test yet.

 

[vix]

A higher FSB does NOT automatically mean more heat. Heat is the result of overall higher speeds and voltages. Theoretically my system can run at 6 x 500 FSB for 3 GHz and do it with with the same temps as if I ran it at the default 9 x 333 FSB. My FSB may be set higher, but if I'm not adding additional voltage to anything and not running it any faster, THEORETICALLY the temps should remain the same.

As far as a Q6600 OC, both of my Q6600 systems do a solid 3.6 GHz, but they both require 1.475v to remain 8 hrs Orthos/OCCT stable at that speed. If you plan on doing that, make sure you have an adequate cooling solution.

 

[TrainTrackHack]

but if I'm not adding additional voltage to anything and not running it any faster, THEORETICALLY the temps should remain the same.

Higher clocspeeds always mean more heat, was there a voltage increase or not. Though increasing clockspeed only results in linear increase, while increasing voltage exponentially increasing heat prouction.

 

[Kewl Munky]

As far as a Q6600 OC, both of my Q6600 systems do a solid 3.6 GHz, but they both require 1.475v to remain 8 hrs Orthos/OCCT stable at that speed. If you plan on doing that, make sure you have an adequate cooling solution.

Well when I check the temp in the BIOS it is at 30C or less sometimes, so I think I have good enough cooling to OC a bit.

 

[GSAV55]

A higher FSB does NOT automatically mean more heat. Heat is the result of overall higher speeds and voltages. Theoretically my system can run at 6 x 500 FSB for 3 GHz and do it with with the same temps as if I ran it at the default 9 x 333 FSB. My FSB may be set higher, but if I'm not adding additional voltage to anything and not running it any faster, THEORETICALLY the temps should remain the same.

Would the change you described have overclocked your CPU? And how do you change the FSB without changing the voltage? What does an unlocked multiplier mean? and how do you change the multiplier?

 

[vix]

Higher clocspeeds always mean more heat, was there a voltage increase or not. Though increasing clockspeed only results in linear increase, while increasing voltage exponentially increasing heat prouction.

I think that the disconnect here is FSB speed vs. clock speed. Yes, an increase in clock speed over stock will increase your temps, however if you run stock clock speed but with a lower multiplier and higher FSB, the CPU is still running at the same speed and no additional heat should be generated. This, of course, is assuming that he has an unlocked multiplier. If he has a locked multiplier, then any incrase in FSB will automatically increase the clock speed, overclock the processor and increase the heat output.

 

[JCaSs1001]

does the amount of multiplier effect stability or is it okay to increase it aslong as FSB is increase accordingly? >more heat>needs better cooling

 

[Kewl Munky]

I only have a core 2 quad, so I believe I have a locked multiplier.

 

[vix]

does the amount of multiplier effect stability or is it okay to increase it aslong as FSB is increase accordingly? >more heat>needs better cooling

Multiplier works in conjunction with FSB to determine the core operating frequency. 9 x 355 FSB = 3.2 GHz, 8 x 400 FSB = 3.2 GHz, 7 x 457 FSB = 3.2 GHz

If you have a processor like a Q6600 with a 9x multiplier, the default is 9 x 266.6 FSB = 2.4 GHz. If you raise your FSB from 266 to 333, your speed increases from 2.4 GHz to 3 GHz. Increasing the FSB to 400 will boost your clock to 3.6 GHz. A lot of people have a hard time getting Q6600 to 3.6 GHz, so another option would be to drop your multiplier to 8 and increase your FSB to 400, increasing your speed to 3.2 GHz.

What your system can handle is will depend greatly on your CPU specs, your system RAM and your motherboard.

I only have a core 2 quad, so I believe I have a locked multiplier.

A C2Q processor is DOWNWARD unlocked, i.e. if your default multiplier is 9, you can use a lower multiplier but not a higher multiplier.

 

[fade2green514]

well, if you're talking about intel yes. the lower the fsb and the higher the processor frequency (and therefore the higher the multiplier) the better it will be for overclocking.

for instance my e6300 is bottlenecked by its low multiplier of 7. its fsb is 1066mhz which is simply 4x the system fsb (266*4) and the processor frequency is 1.86ghz. with a higher multiplier i'd be able to push it further, but my processor cost me less and thats the reason it costed less.