Originally Posted by white owl
Seems like you have your mind made up.
If you don't like this guide we have a few others.
[Deleted old post]
Sorry, I made a derp. The BIOS mod is fine. I created a new Windows user account and it indeed DOES clock/volt down when idle. For some reason something running in my main user account is keeping it locked to the base TDP and never lowering.
Update: The main problem was the "Prefer maximum performance" suggestion in the OP, apologies for dismissing your driver suggestion. With this enabled, the clock will *never* go below the max clock anyway (the boost entry in the stock BIOS). What this means to me is that my newer BIOS is actually behaving correctly. I mean, it makes sense that a Max Performance setting actually locks to max performance, right?
Or maybe it was a driver bug/change when the "Optimal" setting was introduced - since this guide was written before that feature was added, I think.
So anyway, I set my card to Optimal now.
I also kept two clock entries on the first tab of the BIOS editor; I set TDP @ 405.5 (lowest clock available) and kept the second entry at my max clock (1455.5, which is the max clock already set in my card's boost table). I just have a weird issue now where Kombuster (in fullscreen) will peak at 108fps, then after it warms up it drops down to 85-90fps - with absolutely no PerfCap reason at all :\ it's only Kombuster though so I'll see how real-world performance goes. I still get a little over 4100 on Time Spy benchmarks and the clock never drops from 1455 when under load; my idle and desktop-use (e.g. typing this post) power usage for the whole PC is now down to 80-90w (from 140-160) so I'm happy with the power savings and no perceived performance loss so far.