90W vs 65W power supply

[Wendy]

I have both the 90W and the 65W power supply. The 90W came with my W500 and the 65W came with my recent acquisition of the R61i. The 65W is offered as an accessory for the W500 but under the "Help me decide" states that the 90W is for use with Discrete Graphics. The question I have and I think I already know the answer...but want confirmation from the Thinkpad 'Brain Trust':

Can I use either supply with either PC? My thought was to leave the heavier 90W at the house ( I actually have two since I have the dock as well) and use the 65W for travel since its lighter. So this would mean that the R61i would use a 90W and the W500 would use the 65W when traveling. Is my assumption true that the 65W will just charge slower or will it do any harm to the W500 with the discrete graphics. And will the 90W overcharge the smaller R61i?

Thanks in advance.

[ZaZ]

I'm certainly no savant on the matter, but I would think if it's a listed accessory you could use it. I've got the Advanced Mini Dock, which has the 90w adapter. On occasion I've used it charge my R60 not in the dock. I've never had a problem with it. I would think the same of the R61i.

[rkawakami]

90W supply can safely power either system. It won't overcharge the R61i. The R61i was specified to use the 65W supply because of the Intel Graphics chip (GMA). The W500 has a selectable graphics system. It can either use a similar type of GMA chip or the "discrete" ATI graphics chip. I'm assuming that when the GMA video system is being used, then you can safely use the lower wattage power supply. I don't know enough about the W500 to say that it would automatically switch to the GMA graphics if you plug in a 65W adapter. I found this on the Lenovo site:

New ThinkPad T500 and W500 series models feature Intel Core 2 Duo processor technology
<snip>
This feature enables you to maximize battery life or performance by switching between integrated and discrete graphics. Powered by ATI's switchable platform, the system detects ac/dc power and switches automatically between the types of graphics. Enhanced Battery Stretch also switches automatically to improve battery life. You can also choose to switch graphics using a hot key. When the system is on battery (dc), graphics switches to Intel Integrated 4500MHD. When plugged in or docked (ac), graphics is discrete.

Note that there's nothing said about two different wattages in power supplies (AC).