[M4600] if use 90w adapter, how slow the CPU/GPU could be?

Could be a safety feature to prevent a low power adapter from melting.

But Dell screwed up big time because it seems the identifier chip in these adapters fails often and then the BIOS goes low power with no way to override. It just seems so heavy handed, because it could instead supplement with battery juice or set a medium power target instead of dropping to the level of a 2005 CPU.

In my case (Linux) I found a boot parameter that seems to work: processor.ignore_ppc=1

 

You sure the 180 watt isn't enough for the 6600? I used my friend's 130 watt on my 6600 listed in my sig and arkham city still benchmarked at the same fps as using my 240 watt. Although I'm curious how much it'd throttle with a 90 watt.

If you're looking into a 90 watt I'm assuming this will be for plane use since that's my goal.

 

I am planning to buy a Precision M6600 with i7-2920XM, but it does not come with an
AC adapter. At home, I have a 90W adapter which I would like to use for one month at least.

The reason is to give enough time for my "testing" phase, so that I won't spend $100 on a 240W adapter unless the laptop stays.
I have just returned a laptop for malfunction after 3 weeks and have already bought extra ram for it.

I would like to know if it's possible to charge the battery with my 90W adapter. I understand it will take longer to charge and I am ok with not using the laptop while charging. Even let it charge without turning it on is fine. This would be a temporary phase.

Thanks,
Dani

 

You should be able to charge the laptop with the 90W adapter if the laptop is off or sleeping. If you have Optimus enabled, you might be able to charge the laptop while it is running if power use is kept to a minimum.

The computer will perform poorly when the 90W adapter is connected. (It will actually perform better on battery, but not as good as it would with a proper 180W+ adapter.)

 

You should be able to find a genuine used adapter on eBay for ~40$, that might not affect your testing phase, but it'll save a few bucks if you so choose to go that router. By the way, adapters for the M6700 will work just as well.

 

The behaviour is by design and is part of Intel SpeedStep Technology. Its applied at the BIOS level and if you go into the BIOS (Dell M4600 or M6600) under the performance section and disable Intel SpeedStep then instead of dropping the processor speed when it sees a low power (90W/130W when its designed for a 180W) it will leave it at max performance the whole time.

Speed Step works with a Windows Driver in Win7 but obviously these don't exist in Linux so the only way to fix this is to disable speed Step in the BIOS.

My own experience on a M4600 (Lower dual rather than quad core i7) is it charges, just, when Speed Step is off on my 90W power supply that I carry around for lightness. You may find that with a QM quad core i7 the battery doesn't charge or even slowly declines. A 130W supply should be fine with any processor.

When Speed Step is on it looks for the rated 180W supply and runs full speed when it sees it. Bizarrely you will find Speed Step will run at full power when on the battery only!

Hope this explains what's happening and why and how to "fix" it.

Cheers,
Ian Mountain