iMac i7 loud fan on DVD access

[huha]

Hi,

I've got a problem with my right fan. If I rip DVDs using MakeMKV, the DVD fan is going up to almost 3800 rpm (and this IS loud!). The interesting thing is that the DVD drive temperature reported by iStat stays below 50 degree Celcius the whole time. After the rip has been finished it takes some time then the fan returns to the normal speed(<2000rpm).
Can anybody confirm, that this is the normal behaviour or is this a problem with my system?

Regards
Daniel

 

[huha]

Found an interesting fact: If I copy the files using "cp" to my harddisk, the fan stays at the normal speed. Seems to be a special problem when using makemkv