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Overclocking general questions

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  • Overclocking
  • CPUs
  • Southbridge
Last response: in Overclocking
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May 2, 2008 3:45:24 PM

Can someone explain to me, or point me to a good site that can explain some things.

Im not really clear on the relationship in overclocking between the northbridge, southbridge and cpu. For example, can I overclock my cpu without increasing temps on the northbridge or do they go hand in hand? How does the southbridge play in this?

Also, what about ram. For overclocking, are there special considerations between 2g and 4g (as an example). I have 2g now and have another 2 on the way. I will be using vista 64, but will 4G negatively impact my overclocking ability?

And is it possible to overclock the cpu without overclocking the ram?

I know these questions are all part of a bigger picture on how the architecture works, but Im definately missing some pieces.

Would love more info to help me fill in the gaps!

Thanks!

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May 2, 2008 4:27:16 PM

This might generate a lot of responses, or might not. There are a lot of resources out there to help you.

Start by searching on overclocking <your motherboard>. Each board does it differently.

Generally there is a core clock that drives most of the components. The name is not always consistent but will be in the range of 200 to 400 MHz. Lets call it the core clock. The core clock feeds to the CPU and the chipsets. On many systems the core clock is fixed.

There is a multiplier setting that will generate the CPU clock (you may or may not be able to change it). On my system my core clock is was raised from 266 to 333. My multiplier is 10 which gives me a CPU freq of 3.3GHz. At the default of 266 my CPU speed was 2.66GHz.

But that same core clock increased my FSB to 333x4 which is 1333 FSB (FSB is always 4x the core clock). The FSB is usually an Intel issue and AMD may be different. I am not aware of systems that allow this relationship to be any different. Personally I would try to get my FSB as high as possible as Intel multicore CPU's like it. I then try to moderate CPU speed to balance heat and voltage increases.
Note you cannot always raise your core clock as it does affect so many different parts of your system and it will find the weakest link quickly.

RAM

USUALLY the best performance comes with using two sticks of RAM. 4 sticks MAY force lower clock settings upon you. Again read up on your motherboard.

That core clock also affects your RAM clock. RAM is typically twice the core clock so in my 333 core clock example my RAM speed would be 333x2 or 666. That would be DDR2-666. I can change the clock ratio of my RAM by fixed amounts defined by your BIOS. This would allow me to get more memory bandwidth but there is a penalty for not being synchronous with that core clock. To over clock that RAM you need to buy higher speed RAM or it wont even work. You might need DDR2-1000 or DDR2-1066 with some of the clock ratios. RAM over clocking increases its heat but not much in other components.

HEAT - any increase in clock will increase temps. At some point you will reach a level where you need to increase the voltages of various parts to continue to increase speeds. Voltage increases raise temps pretty quickly. Personally I wouldnt even bother overclocking without a good aftermarket cooler. But you can raise speeds nicely without a voltage increase.

Increasing FSB voltages causes temp increases in the CPU and northbridge/southbridge.

The best success comes from sitting down and thinking through this in advance. More heat affects the chassis, more voltage and speed affects affects the power supply - you may not have enough juice. Buy the right components in advance and you can have spectacular results.

These boards are full of people who are on the ragged edge of heat dissipation, power problems, and components clocked too high.

Good places to go are the CPU manufacturers web sites where they will show you block diagrams and so forth.

Good luck - hope that helped....
!