G5 Dual 2.5

[Brett B.]

I was out doing a bit of dumpster diving over the weekend and scored a G5 with the dual 2.5, 1.5GB RAM and a SuperDrive. Doesn't appear to have any coolant leaks, either. I'm having some issues with it occasionally not booting and not recognizing some of the memory, hopefully it will be an easy fix.

 

[uniserver]

i've never herd of anyone throwing the aluminum g5's in the dumpster, this is the first i herd of that.

 

[Brett B.]

Neither have I, but it's amazing what you find. Over the course of a year I have also found a Dell XPS box with a Core i7, and a HP with a quad core AMD Phenom with 6GB RAM (in the same dumpster, no less.) It obviously has some issues and keep in mind it's probably 6-7 years old, so...

 

[BGoins12]

i7? Quad core Phenom? You must tell me where this dumpster is.

 

[Brett B.]

Behind my office

The G5 must have some serious issues. It worked fine until I removed the memory from it and installed some larger modules. Now it freezes or just won't boot at all regardless of what memory I put in it. Quite annoying. Might just save the case for a mod or something... I always wanted a G5 but they are so finicky.

 

[beachycove]

Check for a coolant leak. Many are undetectable until the processors have been removed and inspected. You have the typical symptoms.

 

[Brett B.]

I will do that tonight, now that I am done with a couple other projects from last night. I figured it was either a coolant leak or possibly a cracked solder joint/BGA issue. I can deal with a coolant leak but troubleshooting BGA issues is always frustrating.

 

[iMac600]

Last time I had a G5 intermittently freeze or fail to detect memory, the culprit ended up being an intermittent BGA joint on a large IC (presumably Northbridge/Chipset) on the reverse side of the board. It's below the orange/copper portion of the heatsink in this image:

However, my machine was a Single 1.6GHz Air Cooled G5. I had heard recently of later G5s, including the Dual 2.5GHz machines exhibiting the same problem with the solution being a solder reflow, as I found when I came across this video. One critical piece of information I have to mention is that due to the size and construction of these boards, it is very easy to warp them if too much heat is applied in a centralised location. The creator of the linked video appears to have some success with using an oven to reflow the board.

Of course, your mileage may vary and it's difficult to be certain if this is actually the issue with your particular machine, but the symptoms sounded all too familiar so I figured it was worth chipping in on it, even if you attempt this only as a last ditch attempt.

 

[Brett B.]

I will have to check it over and do more troubleshooting. The BGA solder crack issue just seems so likely. Here's the kicker... I brought it home, turned it on, and it worked for a long while until I removed the memory and reinstalled it. It's been intermittent since then. When I reinstalled the memory, I noticed that the logic board flexes an awful lot ... I figured that I might have cracked an already weak solder joint on the back side of the board, or something. There seems to be very little support directly behind the memory slots.

 

[uniserver]

one thing you can try, is take your 1500 watt space heater, aim it inside the case for about 15 minutes… flip it on, if it comes on/ ,,, see what happens.

 

[Brett B.]

I'd rather try heating it in my oven, or with a heat gun... too much plastic inside the case to distort with a space heater.

 

[CelGen]

The #1 part to go faulty is the memory controller. Even IBM posted a technical bulletin stating that there was a severe problem with the use of ROHS solder with the chips. If you ever start to see memory issues and intermittent junk like that, DO NOT TOUCH THE RAM OR THE CPU as coming from experience this ALWAYS disturbed the chip enough to cause the BGA joints to completely fail.

From a previous employer, for every 15 G5's we got in per month for recycling, 13 had cold BGA joints and were dead, another would ahve a dead power supply or a leaky LCU and the odd one out would work and those we sold wholesale or if we were feeling dangerous, we blasted them out with compressed air, put a fresh install on them, and sold them AS-IS.

There was a website somewhere that went through the full instructions on how to reflow the memory controller and hopefully fix the problem for the time being. It's a time critical process and you need a fairly good thermometer to get your oven to follow the reflow curve.

 

[uniserver]

by Brett B. » 25 Apr 2012, 14:37
I'd rather try heating it in my oven, or with a heat gun... too much plastic inside the case to distort with a space heater.

I wouldn't want all your plastics to "distort" haha.

 

[beachycove]

More localized heat would surely be better, and in that connection, this might just be inspirational, assuming you could find an iron the right size. Can't make it too much worse than it is, can it?

 

[Brett B.]

I think I may just pull the board out and hit it with my heat gun. If it doesn't work, oh well! The case is excessively cool for hacking purposes if nothing else. Hopefully I will have some time this weekend. It's supposed to rain so that would really help motivate me to do indoor projects.

 

[uniserver]

just aim the space heater in the case… get it hot for 10 min and see if it turns on. it will be fine. its not a big deal and will tell you right away… i tried that with 3 machines, 2 were this common issue of BGA memory controller, the other was simple, pulled the video card out , popped it back in

and it was working flawlessly, right now i have a 2.7 ghz DP, liquid cooled,(hangin out under my desk) i tell you that once i have just one issue, i'm gutting the case,,, but so far its been rock solid, and i clean my my machines out every 6 months with 60 psi,(blow wand) a real air compressor in the garage,

i would like to guess that dust bunnies build up under the motherboard causing extra heat to build up, i'm sure the ROHS lead free solder does not help, however its easy to blame the solder, if you have your ventilation and your heat dissipation devices are working properly there is not going to be excess expansion , because the heat will be dispersed properly. unless there is a intensional design that ensures repeat business after a certain length of time.

witch i do not rule out! evil bastards lol.

 

[Brett B.]

I'm just not convinced that the space heater will actually cure the problem. RoHS lead-free solder melts at 422* F... I can tell you that my space heater does not get anywhere near that hot, and even if it did, to get the motherboard hot enough to reflow the solder in that area would incinerate everything else in the case. The physics behind the space heater trick just don't make sense. I have tried the "towel trick" with my xbox 360 for the same BGA issue and it just makes it worse, and that sucker gets HOT.

My heat gun, on low, will blow hot air at 482*, plenty hot to reflow the solder. I will try that first since I can get localized heat and not worry about damaging other components, even if I do end up with a warped logic board.

 

[uniserver]

lol i am not trying to cure the problem… we are trying to diagnose the problem,

IF- the space heater causes the computer to work, Then - then its something like a BGA issue or

loose connection that expansion from heat fixes, Then you get a idea of the kind of issue you are dealing with,

in one of the 3 powermacs i worked on, i found the issue was just the video card needed to be pulled and reseated...

with the space heater:

( were talking like 160 F tops ) by the way,,,

IF - the issue happens to be BGA, Then- you will need more then just a heat gun,

to fix the issue-

 

[iMac600]

Alright...

- I noticed the issue with my G5 became much more frequent after removing and reinstalling the memory. In addition, doing so would sometimes temporarily cure the problem. The memory slots are a high flex point and the large IBM IC on the back of the board is quite close to the memory slots. Therefore, some flexing can create and even temporarily resolve such problems, so don't be surprised.

- Using a space heater aimed directly at the memory slots will sometimes allow the machine to function correctly. This is through heat expansion of the solder joints allowing the chip to connect with the logic board, which allows for a successful boot. It won't cure the problem, but it does aid in troubleshooting.

- Be VERY careful when using a heat gun. As I mentioned in my above post, the last time I used a heat gun, the concentrated heat was enough to warp the board. If you're going to go this route, heat only the suspect chip, don't go crazy anywhere else, and keep the amount of time required for heating to a minimum.

- Be aware that you will need to strip the board of any tapes and plastics such as heatsink pins and what not. You essentially need to strip the board as far as you can go in the area you're about to heat without actually pulling components off the board (memory slots and all will be able to withstand it).