Originally Posted by Desp
I have the same question, I have a x2 4200 and am running it at 1.45 up from stock of 1.30, my question is, is heat the only thing that ruines a CPU when you give it more volts? I don't really feel the need to be an uber overclocker at the expense of ruining a good CPU. I'm at 2.75 ghz from stock of 2.2 and this is the absolute lowest voltage that it's stable on. With the stock CPU and voltage I had load temps of ~130F, with the current voltage and speed, with a water cooler I'm running load temps of 110F.
it's a combination of things. at AT
a similar question was asked and two members of AT that also work for Intel, shed some light on the subject. it's a very enlightening post so i urge everyone that's interested to read the whole thread.
original question posted by biomanz:
"We all know overclocking generally shortens the life of components, but is it because of the extra heat or is it simply because they're running at a faster pace than they were built to run at? The main thing I would like to know is: Is there any harm in overclocking [something] as fast as possible as long as the temperature stays at a safe level, with as much voltage increases as needed to keep it stable? I could OC my vid card and up the fan speed up while keeping the temp down, but still can't help but wonder if its life will still shorten."
/snip from pm
"There's a linear dependence on mean-time to fail (MTTF) on a CMOS part to temperature, there's a square dependence on voltage to MTTF.
In non-statistics speak, increasing the temperature a bit will make your chip a little more likely to die. Increasing the voltage a little bit will have a much bigger statistical liklihood to kill your chip.
if that's too much, then he tries to break it down so it's easier to understand.
/snip from pm:
"There are 4 ways that chips break:
electromigration: metal atoms in a wire move around because lots of lots of electrons hit them. Move enough metal atoms and the wire will either short with another wire, or have a hole in it and stop working.
TDDB: the insulation material that separates two key parts of a transistor breaks down creating an electrical short - which breaks the transistor. In most cases, if any one of the hundreds of millions of transistors breaks, it will break the chip.
hot-e: a key parameter of the transistor called "Vt" (threshold voltage) shifts over time - which essentially slows the transistor down. If it slows down enough, then the chip will calculate an incorrect value.
BTI: Similar to hot-e but for a different type of transistors and happens for a different reason. Usually fixed in the factory.
In all but hot-e, increasing the temperature a little makes the chip a little more likely to break (this is all statistics... there is no "do this and this will kill your chip..." it's all a matter of probability). In hot-e, lowering the temperature makes it worse.
In all of these, increasing the voltage a small amount makes them much more likely to break the chip.
As to why 10% more voltage is much worse than 10% more temperature, well let's take the example of electromigration and look at it in detail.
Wires are made up of atoms all lined up. Electrons flow through these atoms. An electron is a very small thing, and atoms are a lot bigger. So the idea of an electron moving an atom around is a lot like someone trying to move a car (atom) by shooting a BB (electron) at it. Clearly to ever hope to move a car by shooting BB's at it, you would need a lot of BB's... a storm of BB's. But if you get enough, the car will move. Millions of BB's and that car will likely start getting pushed around. The temperature of the chip could be thought of as how slippery the road is. A little bit more slipperiness isn't going to help a BB move a car. It helps a little but not a lot. On the other hand, the voltage determines how many BB's you have, and it's not like 10% more voltage is 10% more BB's (electrons), you get a lot more than 10%. And worse than that, because increasing the voltage in a chip also increases the temperature (all things being equal, like same heatsink, same air temp, etc.), increasing the voltage is a double-whammy.
The others are similar... but more complex to explain (I'm still not sure that the experts really completely understand the low-level details of both TDDB and BTI...).
i took excerpts from the replies to shorten it down to try and get the point across. it's a great read
so again, i urge those that are interested to read the whole thing.