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  Upping Vcore, CPU Overvolting Explained 
  Mar 06, 2002, 07:30am EST 


By: Dan Mepham

And there you have it -- that's how increasing core voltage helps you squeeze a few extra MHz out of your processor. Anyone who has overclocked before, though, will note that extra voltage will only take you so far, and that eventually you reach a point at which more voltage just won’t help anymore. Nevertheless, a few percentage points of voltage over default is usually quite helpful.

Those of you familiar with the mathematics of an exponential curve will note, however, that it is one of diminishing returns. Increasing the core voltage by 10% may help us reach the default voltage significantly faster. However an increase of 20% will offer only incremental gains over the first 10%, and an increase of 30% will do almost nothing beyond 20%. In other words, doubling the core voltage will absolutely not cut the transient time in half, and in fact, will only slightly reduce time versus the first 10-20% increase. This helps to explain why, often, a 10-20% voltage increase will help a great deal, but beyond that, extreme (indeed, unsafe) voltage levels are frequently required to squeeze out even a bit more speed.

How a system will behave when this voltage ‘clipping’ occurs is greatly dependent on the software as well. When the CPU starts interpreting 1s as 0s, and visa versa, the end result is that it performs calculations wrong. Whether the system crashes, hangs, pauses, or just acts bizarre is just as dependent on the software at this point. A miscalculation on a critical, low-level, operating system instruction might cause a complete hang, whereas a miscalculation in a game may simply cause that game to crash and terminate, or may even go unnoticed.

Also, we should note that increasing the voltage beyond specification can and will prove hazardous, if proper care is not observed. More voltage and higher speeds mean more heat, so if you plan to increase the voltage on anything, make sure you have excellent cooling. Furthermore, long term exposure to higher voltages can shorten the life of your processor greatly (think about what would happen if you constantly slammed your door closed like a maniac -- how long would it last then?). We’re not in a position knowledgeable enough to be able to quantify the lifespan of devices at different voltages, but be assured that too much voltage will decrease component lifespan.

Dan Mepham

1. Introduction
2. How Your CPU Thinks
3. It's All About Tolerance
4. Transient States
5. Putting it All Together
6. Summary

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