> The new kernal for 1.4 seems to increase power usage by a lot. Does this 1.5 have the same effect too?

I would not say that it increased a lot. I have a wattmeter and measure this value regularly.

1.5 have the same power usage as 1.4 "sm".

More hashrate always comes at a price of more power usage.

If you are concerned about noise/temperature - I would recommend to downclock the videocard. When I had my rig in bedroom, I set frequency to about 850-900. It is barely audible at this setting and produces nice heat (it was winter).

When it is in garage - I set it to 1060.