WD SN550: high idle power consumption

SN550 is advertised with exceptionally good power consumption both at read/write and idle. I recently purchased a 1TB version just because of that.

I put it into my laptop where the M.2 socket is only PCIe 2.0 x4. I fully understand the bus limit on max read/write throughput before my purchase.

However, to my surprise, I found the idle power consumption is far from the advertised values (.03W in PS3 state or 0.075W for average active power consumption).

With ASPM/LPM disabled, it idles at about 0.9W. With ASPM/LPM enabled, it idles at about 0.4W. One order more power hungry than as advertised!! It seems to me the firmware never allows the SSD entering lower power modes?

Tomshardware review basically corroborates my observations, in particular this slide.

So my questions to WD engineers:

  1. Could you release a firmware update to fix this issue please?
  2. Or tell me what conditions are missing in order to reach idle power as advertised?