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I found out that the Intel Atom N455 in my netbook can run the x64 instruction set. I don't have any compatibility problems with old x86 softwares and drivers, but I need to save battery power.

I understand that using long mode would make the instructions bigger, and this would probably increase the power consumption. However, long mode will also take benefit of the larger and additional registers, accessing the RAM and the cache less frequently, decreasing power consumption, right?

So, what's more power efficient to use on a computer like this, a x86 operating system or a x64 operating system?

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closed as not constructive by Ƭᴇcʜιᴇ007, Oliver Salzburg, Sathya Mar 16 '12 at 4:04

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Generally there is no difference. For certain compute intensive tasks, 64 bit will be faster, and thus, use less power.

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"faster, and thus, use less power." Not so sure about that statement ;) – Oliver Salzburg Mar 16 '12 at 2:51
@OliverSalzburg, the sooner you finish working, the sooner the cpu can go back to sleep, thus saving power. – psusi Mar 16 '12 at 3:13

Running it 64-bit will save battery by not maxing your CPU out for so long on computationally intensive stuff. When your CPU utilization goes up then you generate more heat. There is no such thing as using up energy as it just gets transformed. Heat is a good example of wasted energy when it comes to computing. So the longer you have to keep your CPU usage up, the more battery life it will inherently take. Honestly though, if you're going to be doing a lot of CPU intensive applications on a netbook, you should probably be using a better processor. lower your brightness, get a ssd, disable items in the bios if not needed, use ethernet instead of wireless, i would say downclock the cpu but that may suck with an atom, reduce startup items, use better cooling. sorry that none of this answers your question, but addresses your concern.

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