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Difference between changing the bus speed instead of the multiplier [Phenom II 965 BE]

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September 7, 2013 7:46:54 AM


This is on a BioStart TA870+. Seems to be stable at 55°C-57°C on full load. Haven't changed the voltage yet so I wanted to know if there's anything I'm doing wrong before I try to mess with that.

So, is changing the bus speed instead of the multiplier basically the same thing? Any Pros-Cons?


TIA for any input.

CPU-Z validation HERE.

More about : difference changing bus speed multiplier phenom 965

a b K Overclocking
September 7, 2013 12:23:39 PM

raising bus speed will overclock your CPU as well as other components on your motherboard such as PCI-E lanes and RAM. as of now, most DDR3 RAM are 1600MHz; 200x8(Ram multiplier)=1600MHz but, you might have a kit thats rated @ 1333 which is what I believe is recommended (i could be wrong).

anyway, overclocking wise, it's technically the same as far as your CPU goes but raising that frequency is gunna overclock other components which might become a much bigger problem in the end. i do remember my 960T (which unlocked to the Phenom II X6 1605T) had no issues with raising BCLK and the main reason i used the BCLK was to overclock the North Bridge.
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a c 295 K Overclocking
September 7, 2013 3:12:58 PM

Hi rRansom and welcome to Tom's Hardware forum.

Here is a little explanation of the difference between overclock using bus speed and multiplier.

The CPU frequency is calculated using two main things: Base clock (or bus speed) and multiplier. The stock frequency for that X4 965 is 3.4GHz, that frequency is calculated with 200MHz in the bus frequency (base clock) and x17 in the multiplier. Now, the multiplier ONLY affect the frequency of the CPU himself, that means that if you change the multiplier to x18, your frequency will rise to 3.6GHz.

The other side is the bus frequency, this item determine your CPU frequency as well as the RAM frequency, HT frequency and NB frequency. With this said, if you change for example your bus frequency from 200 to 220 as you have it in the CPU screenshot, not only the CPU frequency rise, the RAM, HT (QPI link) and NB (motherboard tab) also rise. But what that means?

Well, overclocking with bus frequency is more difficult since you have to keep the RAM, HT and NB in the stock operational frequency while you change the CPU frequency, in this way, exist a lot of things that can fail.
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a c 239 K Overclocking
September 8, 2013 3:37:58 AM

rRansom said:
So, is changing the bus speed instead of the multiplier basically the same thing?


They are both ways to overclock the CPUs output, but the multiplier only method overclocks the CPU itself resulting in higher CPU load heat, overclocking the FSB affects not only the CPU but the rest of the motherboard as well, throwing some essential settings past stability.

Increasing the FSB is usually done by those that don't have adequate cooling to be increasing the multiplier, as past a certain point increasing the multiplier requires increasing the CPU voltage that increases heat load, that has to be accounted for, or your multiplier raising only goes so far.

rRansom said:
Any Pros-Cons?


FSB raising requires much more stress testing time to reach stability, and even when you think you have it stable something as simple as opening your favorite game can bring your house of cards crashing down around you.

IMO raising the FSB is not the route to go at all, however to raise the multiplier of your 965 you need a good aftermarket cooling solution, I had my 965BE to 4200mhz rock solid by raising the multiplier and vcore, and a CPU-Z validation at 4300mhz.

If you want to learn how to overclock your 965 by raising the multiplier the link is below.

http://www.tomshardware.com/answers/id-1874931/amd-black-edition-overclock-guide-raisng-multiplier.html

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