Ok guess we were talking about different things then
Anyways, now I just hooked up another external pump just for the fun of it and for testing. Water temperature doesn't really change but CPU temp does, since the flow rate changed from about 60-65 to about 90-95 l/h.
Does this in any way hurt the compactstream pump? If it is forced to spin faster than it wants? Or does the extra pump simply help out, so it's a good thing really?
Also, I was told it's possible to turn off the internal pump completely, but I don't know how?