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Pentium M's - Reg / Low-V / Ultra Low-V

Last response: in CPUs
December 4, 2004 2:34:01 AM


I would just like some opinions regarding the various options for Pentium M's (the regular ones, the low voltage ones, and the ultra low voltage ones). Specifically I would like to know the performances of them with respect to each other, because I would like to know the tradeoff between performance and battery life.

Also, would a low voltage @ 1.1 ghz perform equally as an ultra low voltage @1.1 ghz? Or would one outperform the other??

Thanks in advance!

December 4, 2004 9:42:36 AM

Good question.
December 4, 2004 1:25:13 PM

If everything else was equal, they would perform the same. With the only difference being .13micron verses .09microns.

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December 4, 2004 1:54:16 PM

first of all, thanks for the reply

so what exactly is this difference of 0.4 microns?? is it the lower power consumption or something else??

and what if i have a regular pentium m at, say, 1.7 ghz and i clock it to 1.1 ghz.. how would that compare with the low and ultra low voltage versions?? (in terms of performance and power consumption)
December 4, 2004 4:57:33 PM

well actually not necessarily, because i will only rev it down when i'm on battery power.. when i'm using AC i will rev it back up.. (i believe there are softwares that can do it for me without rebooting the comp?)

and i'm not 100% sure, but the cost of an ultra low voltage 1.1 ghz processor would cost just as much as a 1.7 ghz regular one.. can any1 confirm that?

again i dont really know the details about these processors and would like to know more.. any comments are welcome.. thx~~
December 4, 2004 6:46:40 PM

The Dothan core CPU uses the .9nm manufacturing process but comes in both low voltage and ultra low voltage forms. The power consumption of these CPU's has nothing to do with the manufacturing process.
December 6, 2004 3:11:24 PM

WHat I think the differences are between the LV and ULV processors are just that the ULV processors have passed testing to be stable at a lower core voltage than the LV ones. An LV at 1.1ghz and a ULV at 1.1ghz will probably perform the same, but the ULV will use a little less power because it's running at lower voltage (thereby using less watts). So, if you take an LV 1.7 and downclock it to 1.1ghz, you will still be using more watts than a ULV at 1.1 because of the core voltage difference.

Hope it helps, and I hope I'm right.

December 6, 2004 9:58:41 PM

ya thx for the reply.. i'm thinking about the same thing too.. but i was just hoping some1 had links to like actual statistics / comparisons done between the LV and ULV... i tried to use google to search but couldn't find anything of much use to me~~
December 7, 2004 6:52:23 PM

I don't have any links to prove it, but yeah, fishmahn has it right. The performance isn't any different. The difference is in the power used and heat generated. Of course there probably aren't links to articles proving it because it's one of those things that really doesn't need proving. If it's the same core running at the same speed then it'll have the same performance. The voltage isn't going to cause that to be any different.

The LV and ULV use less voltage, thereby producing less wattage of heat, and thusly run cooler and save battery life. :)  That's pretty much their only point, but it is a good one to those who care. In theory they'd make better overclockers too, but since they cost more than a standard voltage version, that kind of defeats the purpose of saving money by OCing. Heh heh.

So anywho, in theory you could underclock a regular CPU. In practice it won't gain you nearly as much if you don't also undervolt it. Even then you'll probably never get the power/heat down to being as efficient as a LV, and definately not likely to get down to ULV levels. Efficiency from ground up is a lot easier than the other way around.

But if you're looking to save battery life on a laptop then look at your monitor backlighting levels. Backlighting is generally a big power eater. Turn it down and you'll save a lot of juice.

For that matter speakers can be hogs too. Using those ultra-small really-low-voltage earbud headphones instead of the built in speakers (and turning down the volume as well) can save a bit of power as well.

The only problem with low voltage headphones on computers is that many computer sound systems pick up a lot of low level noise from the PC that you might never hear with speakers or normal headphones but you can hear all too well with low-voltage headphones. :\ On my work PC I can even clearly hear the signal noise from hard drive access as a high-pitched squeal if there's no sound playing and I crank up the volume. Come to think of it, I have to try that on my home PC sometime and see if it's any better...

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