It's a laptop workstation - power settings in general are not present in the bios. Power supply is ok for the machine. As I have said in my post GPU frequency scales just fine in Windows 7 on this machine with the same bios settings and everything.
I have done some more tests using PerfLevelSrc tweaks as explained here:
I observed 4 different distinguishable performance levels - 2 on battery and 2 on ac.
I used nbody and bandwidthTest from cuda sdk to measure relative performance. Some numbers I got:
Battery power, locked in lowest performance: 200 | 1300 | 5
Battery power, locked in medium performance: 600 | 3900 | 16
AC power, locked in lowest performance: 1400 | 3300 | 19
AC power, locked in medium performance: 2800 | 8500 | 55
Some explanation - locked in lowest performance means that nvidia panel shows perf=0 mode. Locked in medium performance - perf=1 mode reported. When I try to lock it in perf=2 I get perf=1 reported and same results as perf=1(including 405,324MHz reported frequencies). For the numbers - first column is device-host/host-device bandwidth, second is device-device bandwidth, third is FPS in nbody. I ran each app a few times on each mode - deviations were no more than 5%.