65W on T400 with Discrete Graphics

I have a T400 with discrete graphics. I was on a trip when I purchased a 65W powersupply from a local store selling lenovo products and he assured me it works. I wanted an extra powerplug anyway as a permanent solution for a desk, and another (the one that came with) as the one I keep in the briefcase (or vice versa). Anyway the 65W is smaller however I noticed that the one I got with the machine is a 90W powersupply. It is slightly larger. Now that I am home, I am unable to exchange this product now (or at all even if i was there looking at what is stated in the receipt, probably business practice in asia).

Is it ok to be using the 65W powersupply for my T400 having discrete graphics, WHILE using discrete graphics? I understand they give 65W powersupply to integrated graphics ONLY machines.

 

Probably it's OK to use it as long you're not using it to charge the battery while using the machine and putting a load on it (eg. playing a game), who knows how much watts the machine pulls when it's being used at full load so that charging the battery would put a lot of strain on the 65W adapter.

 

Generally, it should be okay. Like t30power said, I would not try to charge your battery or plug in any other external devices (2.5" hard drives for example) while stressing the T400.

 

I think folks are being overly cautious. I've regularly used a 65W adapter as my "travel" adapter for my T400 and left the 90W home for the past ten months.

Note that the advanced mini dock comes with a 90W adapter; this dock supports the W500 and that adapter is intended to run the dock and computer.