- Solid hardware support, including: built-in sensors for Intel and AMD CPUs, nVidia and ATI GPUs, and HDDs via SMART. mCubed T-Balancer, and many SuperIO chips (for a complete list check the website)
- Fast and simple to use (no configuration needed), with a straightforward, uncluttered interface.
- Graphics plotting
- Works under Windows 32-bit and 64-bit
- Works under Linux with no changes (just use Mono)
- Free and Open Source
What it's lacking mainly the ability to control fans but TBH I never found that function was well implemented or reliable enough. And in these days of smart mainboards, it's not that useful either.
The author is quite cooperative, and will implement support for your hardware if it's missing, as long as you help with testing.
If you wanna give it a spin:
http://www.openhardwaremonitor.org