N0503 high temperature issue

Hi all.
I have just purchased the N0503 combo NAS & was setting it up with 3 x 1TB WD disks in Raid-5. Whilst it was building the RAID which took about 4 hours it shut down twice to prevent the CPU from overheating which was around the 70 to 75 deg. C mark. The fan is spinning at 1450 RPM, my office is air conditioned & it's out in the open.

Needless to say I'm a little worried about this. Right now CPU load is 0 to 10% and it's still 58 deg C. the hard drives feel fairly warm to touch as well.

Any thoughts on this would be appreciated as I have little experience in this area. I have put a ticket into Thecus about this but they are taking their time getting back to me.

Thanks in advance.
David