Fan boost on startup

This is normal for many boards as well as video cards(video cards being louder).

Some fans may not start nice at lower speeds so the start fast then slow down ensures the fans are all spinning before you reduce the speed.

30 seconds sounds like a bit long for it, but it seems like a normal thing.

With quieter fans it is not even that bad if you do not include the fact that some video cards do it.

What card do you have anyway?

This is normal, nothing to worry about.

I expected it to be normal, but I don´t like it. It´s very loud..
Just wondering if I could change it...
Is the difference with (for example the corsair quit fans) that big?

It depends on the fans top speed.

When my system starts, the fastest fan can not get past 1200-1300 rpm so is considered more quiet then having a 2000rpm fan run full speed.

If you can live with one speed or manual speed control, you can use a fan controller(or 5 volt mod some fans   ) to set the speed once and it will always run that way.

This is not always recommended for cpu fans as with the board in control at least if it gets too hot, it will crank the fans up, while if you set it too low it can overheat with the board not being able to auto control the speed.

That being said, some heatsinks are more then capable of low speed cooling.

btw I have a xfx radeon 7850

but it's the case fans that caranks up

Control it through the BIOS.

I think you may be stuck with it. Unless you want to control then another way.

Just as an example, on my Antec 900 case, I ran all the fans on low(but they have a control switch) so they just ran at that speed all the time.

You can get a fan controller(some fit in the CD bay or even in a rear pci slot) to run them at a lower speed.

They also sell cables to drop the voltage to 5 volts(its just a molex using the red wire as opposed to the yellow wire.). 7 volt adapters exist as well(red to yellow), but users have mixed feelings on that idea.

amuffin, with it running full out then dropping, I do not think they will find a bios fix for it.