Sensors now start in about 2 seconds.
About those weird temps. I've reset the layout and it temporarily fixed the issue. After some time they were back.
For now I've just disabled monitoring of them.
Thank you. Now it shows proper values.
I have few more issues related to HWiNFO and my 290, if you are interested.
It takes about 17s to detect sensors (Sensors button). Most of time it displays:
Detecting sensors ...
GPU ATI #29
(then #30 and #31)
With my old 5870 it was rather...
I'm using HWiNFO64 4.27-2035 and sensors show incorrect GPU frequency.
The card is idling at 300MHz (shown in CCC, GPU-Z, Afterburner) but HWiNFO is showing 825MHz.
Here is screenshot (with GPU-Z for comparison):