When I remove the power cord the internal clock resets immediatly, even after such a short time as 1 second.

I want to rule out any other reason then that the clock battery has died. Maybe that this is normal for the G5 or a MOS bug or something. Have any one else experienced this?

And if it is a broken battery, could it be a sign of severe leakage?

Same issue here.

I presume your battery expired (or lost alot power) since G5 has not rechargeable battery like Pmac G4.
And no, it's not a sign of leakage. Unless it's an old barrel battery (remember Amiga batteries?)

[ Edited by Jambalah 09.07.2013 - 20:31 ]

Just add SetClockNTP to your network-startup.

That makes a lot of sense! Thanks everybody for the input and suggestions

The battery is the same type as in the G4s (atleast in my QuickSilvers), non-rechargeble, can be hat at ebay for few € / $.

Same problem here. I 'll search in ebay to change it.