Voltage Mod Question

[train22]

Why would you ever need anything higher than a 10k ohm resistors?

If I want to mod my board to run at 2.1 or around that a 10k good right? I mean does it stol at those "bustops" or does it jump from say 1.9 to 2.14? Will a 15k-ohm stop more frequently and what's its max?

By the way will a variable resistor work better? Is it what most people use if so?

[Rob Cork]

The important thing to realise is that although you raise the max voltage by a certain amount, you will also increase the minimum voltage by a similar amount. For example, on my A7V I did a volt mod with a 22k resistor which got me from 1.94V (actual measured voltage - the setting in bios was 1.85) to 2.32, so I added about 0.4V. However that would also raise the min voltage by 0.4V, meaning that it was about 1.7V. While 1.7 should be fine, if you use a lower value resistor like 10k as you suggested, that'd probably get you to about 2.5 or 2.7V, but your min voltage would then be getting close to 2V. That's a bit of a pain if the fan on your hsf fails or your watercooling drops dead, and you have to reduce the overclock and voltage to keep your temps ok.

Plus I wouldn't ever run more than 2.3V through my cpu - even for more than 2.1 you really need great cooling. So that's basically why higher values are used - you don't need any more voltage, and it allows you a safe minimum voltage should you ever need to use it.

On the subject of variable resistors, I believe they are used so you can set the voltage carefully. It's difficult to know exactly what voltage you will end up with using a given value of resistor, so by using a rheostat with a high max resistance you can start off high and lower it to get the max voltage you want. It's just easier and safer.

I believe Colin always suggests a 47k potentiometer - you may have to lower the resistance to about 20 to get 2.3V or whatever, but that's better than using a 20k straight off and finding for whatever reason it's sending 3V through your cpu. Again, I think safety is the main reason here.

HTH :)