Saving battery by disabling processor cores in Windows boot options?

I've seen claims on the forum that it is possible to achieve a noticeable improvement of battery runtime by disabling processor cores in the BIOS.

However, this obviously isn't very flexible. I was wondering whether the boot-options in Windows provide a more flexible alternative:

msconfig > boot tab > Advanced options allows one to instruct Windows to ignore a number of cores. That way, you can configure multiple boot scenarios, and choose one or dual-core operation (instead of quad) at startup when you take your system on the road and plan to only use it for light workload.

But the question is: does this have the same (or at least also noticeable) effect on battery runtime as disabling the cores in the BIOS? Anyone have any experience with this?

 

I would just use the windows power management and set the maximum CPU usage to 50% or something, and then undervolt.

The problem with disabling a core is that while it's only using one core, it's still using all the cache and a few other things, all running at the same voltage. So yeah, it'll save power, but since your voltage will stay the same you'll still be generating a lot of heat for one core. I say leave both cores enabled and force a lower multiplier (and hence lower voltage) by making the maximum CPU usage lower.