HP Proliant DL160 G6 blade server

You can visit here, I think this is helpful for you:
http://serverfault.com/questions/330858/hp-proliant-dl180-g6-fan-noise
http://serverfault.com/questions/330858/hp-proliant-dl180-g6-fan-noise

Make sure all the firmware is up-to-date, and that all the drivers have been installed in the OS. If the drivers are properly installed, the fans should only run as fast as they need to. Of course you should also make sure the case is closed. An open server case leaves the fans running at full speed.

If you installed the server and it's OS using the "Easy Setup CD" which came with the server (or which can be downloaded from the HP site if you lost it or don't have the newest version), the drivers and management tools should get installed automatically.

I installed without the Easy setup cd, I can't find it on the site for my server. Bios is already up-to-date. Maybe I better reinstall.

I just found out there is not smartstart cd for DL 100 series.

For that server model it is called Easy Setup CD, not SmartStart. On newer HP server models you don't even need a CD, there it is Firmware based and called Intelligent provisioning.

DL160 G6 fans are controlled by iLO100/BIOS rather than software agents. Assuming firmware is up to date it may be working normally as they aren't all that quiet at the best of times.

Any 3rd party non-HP parts inside it? DIMMs without thermal sensors or disks that don't conform to HP's SMART reporting can often lead to fans running fast. cheap consumer SSDs are notorious for that.

it was a hardware failure