Voltage modifications are getting more and more common these days as the overclocking scene is growing. When you overclock you often increase the voltage to the processor but this only goes to a certain limit. We have taken a look at Abit KT7A, where you can set the vcore to 1,85V at max. After voltmod you can set it all the way up to 2,5! What does this do then? Do I have to do it myself?
To answer the latter: No, you don’t have to do it yourself. You can always send you card away and get the modification done. It’s TJcomputer that offers this service. The price is 295 SEK plus shipping. A bit much for two small resistors you may think. But if you want your motherboard voltmoded and don’t know much about soldering it may be a good idea to let someone else do it. You can of course also buy a motherboard that has already been voltmoded if you’re thinking of getting a new board.

What a voltmod does is to adjust the voltage to a higher scale. Max voltage with this mod is 2,52 volt. You achieve this by setting the BIOS to the highest value, 1,85V. To end up at the regular values, ~1,75V you have to set it to about 1,2-1,3V. TJ’s modification is not just two simple resistors either but two potentiometers. This makes it possible to adjust the voltmod for more or less maximum voltage.


What do I gain from a voltage modification?

That is what we are about to find out here. Often you can overclock your processor further with more voltage. But with a higher voltage the processor emits more heat. Here the voltmod actually lowers the overclocking potential a little. In general the processor can usually be overclocked the cooler it stays. As we increase the voltage and raise the frequency the heat increase and in that way hinders us from moving forward, but not as much as the voltage opens up new possiblities to go higher. So to you gain the most from your voltmod you need a good cooler.

It looks a little like this:


What can you expect ?

Well that depends a lot on the cooling, but with good cooling combined with increased voltage should give a big increase. We test a Thunderbird 1000MHz with AXIA stepping (known as good overlockers).

Test system :
Abit KT7A Voltmoddat av TJcomputer
2*128mb Mosel
Creativ Geforce 2 GTS
Processor: T-bird 1000MHz

Leufken SocketA water block
Eheim 1250 pump
Senfu dual radiator

A lot better radiator, a cooler from a Mercedes, was available for the test but using it felt a bit unnecessary since the water block is the bottleneck here and the senfu radiator can handle the heat.

We start with the default settings, for the T-bird default is 1,75V. With the default voltage we managed to reach 1370Mhz. Many MHz, but not really satisfying with a T-bird with AXIA stepping. With the maximal voltage you can use with a non-moded board, 1,85V, we reach 1460MHz. Pretty good, but still far from our initial expectations. After some testing it seemed that 2,39V was the best setting. At higher voltage the system had trouble booting. A problem that most likely is because of too much heat because of the high voltage.

Here you see a summary table:

Thunderbird 1000 MHz    
Volt (V) Frequency(MHz) Temperature (C) Heat (W)
Default (1,75) 1370 43 54,3
Max standard setting (1,85) 1440 51 78,3
Best setting (2,39) 1550 61 157

As you can see the voltmod helps a lot when you want to reach the higher speeds! We also see that such a big increase the heat dissipation hits the roof! 157W of heat is not easy to transport away from the processor and the water block can’t quite handle its task. With a little lower temperature we most likely had been able to reach a good bit higher. 3DMark 2001 was used to test the stability of the system. With 2,39V would start at 1609 but was far from stable!! I should add I also tried this with ice water in the system. The computer posted at incredible 1813MHz though! How will the voltmod keep on?

With the right cooling an increased voltage can perform miracles. It is a simple procedure, but still risky such as you loose the warranty. Sending the motherboard off to TJ computer and get it done by a pro is a good option to many. Even if costs a bit. If you’re completely new to soldering you should do it or practice a lot before trying. All and all we have to say it is a very good product/service. Thanks goes out to TJ Computer!


+ Simple
+ A lot better overclocking potential

– High heat dissipation at high voltage
– Perhaps the price

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