I found this the other day in a hardocp thread:
2). The GTX 200 series power saving features do NOT work on an Intel platform. That’s right. I thought I was the odd one out when I saw countless other websites posting about the down-clocks and down-voltages, whereby the GPU settles at 300Mhz Memory to 100Mhz etc when no 3D app is running. What some of them failed to state was that they only achieved this on an Nvidia platform; while ALL the reviews out there failed to warn consumers that this does NOT work on an Intel platform at all. The writeups out there further confuse you by stating the downclocks are achieved in drivers, while only the full hybrid power features, i.e., shutting down the GPU and offloads 2D to the onboard IGP require an Nvidia platform. They just don’t know what they are talking about.
This was confirmed after a 30 minute phone conversation with an XFX engineer, the manufacturer of my GTX 280.
What this translates to is that all the idle power consumption graphs you saw on reviews over the GTX 200 series do NOT apply to an Intel platform. Again, out of the 15 odd reviews out there, not one, I repeat, NOT A SINGLE ONE, bothered to state this clearly. Whats the user footprint in the real world with an Nvidia platform? 0.1% of the PC population?
But this thread, it seems indeterminate of what the cause of the issue really is..