PowerMac G5 LCS, yet another doubt

[bengi3]

I am fixing some spares LCSs to try fix a PM G5 2.7 x2.

I managed to create an expansion vase with some laboratory stuff (see video) and I was wondering if the pressure inside the system can actually reach high values.

In a car engine the water can reach temperatures way above 100°C snd the pressure rises consequently, but here I doubt the two processors can determine such an increase.

This question stems from the consideration of using normal silicone hoses rather than those automotive stuff originally used by Apple.



View attachment 84A2FABC-7039-4D7C-8E66-8B05C087FA7B.MOV

 

[beachycove]

I am not sure just what you are asking, but maybe this will be some help.

My Quad G5's fluid scarcely gets warm, as it is air cooled, after all, and as CPU temperatures tend to hover around the 45-65ºC mark. When they hit the higher end of that range, the fans ramp up noticeably. If CPU temps ever got up to 100, the machine would probably achieve lift-off, assuming it didn't slide across the floor and pull the power line out of the wall first.... 

Refresh your heatsink compound, btw, and you will see very pleasing gains in cooling efficiency in any of the G5s. 

As for expansion, it will be more or less impossible to refill the system without there being some trapped air left inside the radiator and hoses, plus you have the hoses themselves available for expansion. As for those hoses, I replaced mine with clear tubing without a problem, which allows me to see what is going on in the system. I also included a T-junction with a short spur of tubing connected at the very top of the fluid circuit to allow me to get more air out through that spur (it has a removable cap) and more fluid in as required. This dealt with most of the trapped air, as this turned into bubbles that collected in the spur. It only takes an hour or so of running to get the bulk of the trapped air out. I haven't noticed any significant pressure on removal of the cap.

 

[Trash80toHP_Mini]

Draining/refilling/purging the heat brake lines?

 

[bengi3]

Thank you for the replies. I was wondering if those heavy and strong hoses are really needed, given that the liquid doesn't get hot and there's no pressure build up. From the reply it seems that they are not required.

Will keep you posted.