PowerMac G5 Quad "The New Blood Mod" - A guide to flushing, modifying and refilling the dual-pump cooling system.

[dorkshoei]

Oddly I only got 250ml out of both of my radiators. Before I disassembled I could hear coolant moving if I shook the assembly which implied the presence of air. No leaks.

I'm flushing them using a submersible pump and a warm vinegar solution and I definitely appeared to have a blockage on one side, however it cleared fairly quickly.

The pump rate is fairly low, 5.6 liters per minute and that flow cannot be sustained through the radiator. I'm not seeing any debris. I'll have to try the 1/2 fill, connect input&output and shake method. See if anything comes out then.

I put mine on the shelf. I'll get back to it later. I clearly have a blockage in one of the halves. If I blow compressed air through the flow rate will increase to match the good half for a while but then it slows again to maybe 1/2 the rate of the good half. I ran vinegar, aluminum safe radiator cleaning solution etc through it (using the pump) but no dice.

 

[demik]

I put mine on the shelf. I'll get back to it later. I clearly have a blockage in one of the halves. If I blow compressed air through the flow rate will increase to match the good half for a while but then it slows again to maybe 1/2 the rate of the good half. I ran vinegar, aluminum safe radiator cleaning solution etc through it (using the pump) but no dice.

Just worked on mine today. One half looked like it leaked and there was not enough coolant. Although even using gravity, I couldn't manage to get any liquid to flow through the pump. (it was running). I was able however to blow air through all the system and that went fine.

At this point i'm thinking the pump impeller are defective or something similar

 

[Paralel]

So CircuitBored, could you give us an update on how your loop is running?
I have a very weird problem. The lcs seems to build up gas after time. I completely flushed and refilled the loop three times now. Every time I renewed the coolant, the lcs builds up massive air pockets that I can see through the clear tubing.

If I detach the tubing, the lcs literally explodes on me. I am using computer-grade biocide of course, so I have absolutely no idea why the lcs does that. I have a good amount of experience with liquid cooling, I'm doing this in the PC realm for seven years now, I have built multiple systems with custom water cooling. Never ever have I experienced something like this in a PC. I'm at a point now where I start thinking about 1. air cooling the Quad or 2. even build a new lcs scrapping all the G5s parts besides the copper CPU heat sinks to get rid of any contamination.

How long does it take for the gas to build up? If its less than an hour to a few hours, it's a chemical reaction. If it's 8-12 hours to a day to build up, it could be biological.

 

[zChris]

Hello,

Im currently trying to do this mod but i have some question regarding the pumps. The lowerhalf that is springloaded, is that supposed to be removed and not used?

 

[zChris]

To answer my own question yes you need the lowerhalf. Im done with the mod and the computer is on test atm. Currently it passed the thermal calibration tests serveral times.

 

[zChris]

After have had the computer max loaded for about 1.5h the temperature reached 42C on CPU A and 50C on CPU B. I think thats seems to show a success.
The command i used for maxing the cpuload was 10 instances of "yes > /dev/null &".

 

[CircuitBored]

To answer my own question yes you need the lowerhalf. Im done with the mod and the computer is on test atm. Currently it passed the thermal calibration tests serveral times.

I am so sorry for not replying in time! I am very glad that you were able to work it out. Enjoy your revitalised Quad.

 

[Byrd]

At a basic level, that’s the mod - I’m going back in for two Quads I have to immerse the radiator and blocks in an ultrasonic cleaner. All parts have blockage from solidification of the coolant and the pumps are not performing well as a consequence of this.

I'm back here again, having torn down the Quad G5 LCS (dual pump) completely, including cutting the tubing around the CPU blocks and dismantling as much as possible. The dual pump blocks are solid blocks of copper, welded shut unlike the single pump LCS blocks which comprise two halves screwed tight with an O-ring in between. Technically these later model blocks are "leak proof", but the pressure/fluid will just be released somewhere else in the loop if there is a failure point.

On inspection of all parts, so far it appears it is these small water blocks that are the main source of blockage; if you look inside there are long copper tendrils that appear filled with corrosion - or sediment. I can't blow much air through them, although I imagine they are designed to cause some sort of turbulence with fluid to improve cooling. One block appears more affected than the other, which is unusual and I note they have a direction arrow for water flow.

I've immersed the copper blocks in citric acid for a while and now have these and the radiator cranking through an ultrasonic cleaner. Not much is coming from the radiator (in terms of sediment - last overhaul I had some chunks come out but nothing startling), but I'm hoping the blocks can be bought back as they are not easily replaced If not, I've no choice to look into some sort of custom AIO or air cooling using PC parts.

JB

 

[CircuitBored]

I've immersed the copper blocks in citric acid for a while and now have these and the radiator cranking through an ultrasonic cleaner

I think heat might be a good assistant in cleaning those blocks out. I've been meaning to overhaul my mod at some point soon and have been wondering whether or not a steam washer would work without destroying anything. Alternatively, an automotive radiator flushing fluid could work.

 

[Byrd]

I sat both the blocks and radiator in the ultrasonic cleaner for a good hour @ 50 deg C: didn’t think much of it but the telling was a layer of greasy sediment on the bottom of the cleaner once drained, presume most came from the rad.

The waterblocks have been sitting in (kitchen grade) citric acid for some time, shiny on the outside (dark inside), but when I blow through there remains more resistance than what I think there should be, and certainly one block more than the other. I’ve worked on several waterblocks before and while I understand the innards cause water turbulence they should not be this restricted. Will find some more corrosive agent and try again. I do note a tall single fan generic heatsink (eg Coolermaster) might fit inside here X 2.

 

[Byrd]

I've ruled out the possibility of being able to overhaul the dual pump LCS:

- The small copper waterblocks are internally corroded and impeding too much water flow. The small barbs either side of the blocks are also looking worse for wear and ready to break. I can just see them degrading further and leaking in time.
- One of the two Delphi pumps are burnt out
- It's quite possibly one of the worst water cooling designs I've ever come across. I've loved water cooling PCs but to have the Quad G5 working long term under water isn't a suitable solution.

I've looked into using an off the shelf pair of "compact" AIO water cooling units and feel none would be suitable considering the weight of the block (with pump integrated), cost and dimensions of the units. A custom water loop (with dual blocks) might do, but it's very tight for two blocks.

Next up, I'm looking into using a pair of generic PC air cooled heatsink and fan as replacement. Lots of low profile HSF are ~ 100W TDP, and the Quad G5 has ~ 200W TDP in total (2 x ~ 100W per CPU) which might be just pushing the limits as the CPU probably runs hot even at idle. Am looking into something like a server heatsink that's rated to 120 - 150W TDP. Two additional fans nearby would also be suitable.

JB

 

[mg.man]

Hmm... it looks like my original post (and the thread it was in?) about these was lost in the 68Krash... Anyway, I still have these :


They're on the other side of the pond, though, and I've not broken the seals. They were, however, removed from working machines 15 or so years ago...

 

[igor_av]

[...] I do note a tall single fan generic heatsink (eg Coolermaster) might fit inside here X 2.

This would be a great long term solution. Some people used trimmed air cooled G5 heatsinks with good results.

 

[Byrd]

@mg.man thanks mate for your offer, I'd like to think onwards and upwards with a neat air cooled mod over going back to water cooling again. The units are simply not designed for long term use.

@igor_av thanks, it's amateur engineering time having measured up a CoolerMaster 212x HSF, which is rated to 150W TDP. About to purchase two of these. I've measured up other brands, models and have decided on this for cooling efficiency, cost and dimensions.

 

[GameHunter98]

Hello all g5 quad enthusiasts. I have two systems currently. Both g5 and one a single pump and the other a dual Delphi pump. So the dual pump is first one I acquired and it was functional until the system was overheating. So I just put it aside and got another. Well, it was time to resurrect this system. The tear down was pretty easy, and the mod itself took the most time along with cleaning. I cleaned out the loop with distilled water and vinegar.

I wish I would’ve taken more pictures but I was focused in on the goal. Anyway, it took me about a day and one side flowed better than the other. I assume there is a slight blockage in one of the loops. It’s enough to result in a 20 degree difference under load but only a 10 degree difference while idling. Even when under load it all stays below 70 degrees on that "blocked" side when running a long stress test. I was even able to fully pass the thermal calibration! So I am happy with my results to have this system go from sitting broken unused to working and unused!

 

[Byrd]

@GameHunter98 brilliant work, what's the pump top you have there? Out of interest how long did it take you to calibrate your fans - did you find the mouse cursor kind of locks up/goes really slow during calibration?

I've had to take a different tact with mine - currently trialling some generic CoolerMaster heatsinks and fans, with the dual Delphi pump unit in mine having completely corroded itself (radiator OK with ultrasonic clean but CPU blocks packed with solid corrosion), oh and the pumps failed. I'll post up a new guide should I get this air conversion over the line. Just mounted them in (with a lot of metal work), seems fine nothing at all warm, but fans ramping up with no shutdowns as before or error LEDs, calibration is next.

 

[GameHunter98]

@Byrd Thank you. The pump tops are the same Alphacool Eisdecke DDC V.4 Acrylic tops used in the guide. I did switch out some of the fittings to compression fittings on the pump tops vs the other ones. I also had to use some small o-rings on the S bend metal pipes as the sharp edges of the original fittings were a little too pitted to make a good seal even when wrenched down. I'll assume the bottom pump on my unit is weak as well if not it is just the resistance being slightly higher than the other loop. I'd estimate it took about 15-20 minutes in total to complete the thermal calibration. Yes the mouse does not move for me after I start the test, but I do get the text on screen when it passed each test and each cpu in real time. I assume the GUI is just software rendered and doesn't take top priority when testing.

How badly are the fans ramping up? I hadn't touched my g5 in so long I forgot about how the system acts with the inner plastic cover off. Basically kills the intake fans but ramps up the other ones. I then put it back in and shockingly it worked as expected lol.

I am very interested to see the final result with your air cooling setup.

 

[Byrd]

@GameHunter98 thanks for the info - have never done G5 calibration will start tonight, wondered if it took minutes or hours. Tried it the other day but there was a bad stick of RAM and think that thwarted the process as the AHT came up with red text when I went in. Love the appearance of your new pump tops must make filling and draining much easier.

Air cooling will never be as good as water of course but I used my Quad for the first time in years last night. Uncalibrated the CPUs hit ~ 60 deg C max at load before fans ramp but not turbine speeds. Next up are slimline 120mm fans which can pass through air from the top down without impedance, then calibration, and then, a Mac back to life hopefully.

 

[Dude.JediKnight]

Got a dual 2.5 liquid cooled that I need to dig into. I need to get pictures so I can do the research on how to get my specific pump flushed out. No signs of any leaks as far as I can tell, but haven’t dared run it until I at least flush it out.

I’m hoping it’s not too bad, and it won’t need much more than that. Otherwise, I’ll have to see if anyone at the VCF can help me rebuild everything. Maybe find someone who can get the whole pump a sonic cleaning.

At the absolute worst, it’ll just get converted to air cooling, like others have done.

 

[igor_av]

Just mounted them in (with a lot of metal work)[...].

It's pretty impressive! I'd be happy to see how you managed to attach the heatsinks.