4338-20U vs. 4338-30U on a w520

[rcepek]

Hopefully someone can give me some clear text on this. SO I just recently (Yesterday) upgraded my laptop from a W510 to a W520, I already have a dock for the w510 at work and at home and knowing that the w520 used a 170 watt adapter as opposed to the 135 watt that shipped with the w510. I though I would not have to replace the the docks and just buy two new bricks. However I have now found that lenovo changed the barrel connector on the 170 watt adapted to have a notch on them and the docks won't take them with the notch! So right now my w520 is plugged into my w510 dock and I'm seeing no problems? but I'm wondering if it is running at a lower power state or something? I'm sure someone else has or is going through this same situation? Can anyone shed some light on this? or how they worked around it?

Thanks

Rob

[lbreuss]

You only need the 170W if you use CPU, 3D graphics at full speed AND want to charge the battery at the same time.

I am using a 135W PSU for several month now and never had a problem. (I'm using the Intel integrated graphics only (that reduced stability issues with drivers...) and my battery starts charging when below 60%, stops at 80% for enhanced battery lifetime.
The 4338 10U (90W PSU) and 20U (135W PSU) probably are the same docking station, with a different PSU included. The 4338 30U and 170W PSU have a coded connector, because the PSU delivers more current, but the 135W PSU connects as well and works. A 90W PSU will be refused by the W520.