G5 won't start

P

plastictoepiece

Registered
Hi

I'm having major problems with my G5. I tried to restart into safe mode and now It won't load past the grey Apple screen. It's the same problem people have a lot where it just shows an Apple logo nothing else and eventually the fans get really loud.

I think the logic board has gone but I'm hoping someone can tell me about something I haven't tried.

I bought this machine second hand so unfortunately I don't know its age but its a 1.6 if that helps.

Here's what I've tried so far:

Reset PRAM
Reset PMU by button inside
Reset SMU
Reset NVRAM from open firmware which it lets me access [also did reset-all in here]
Reseated PRAM battery
Left PRAM battery out for 24 hrs and tried reseating again
Haven't had chance to test he battery with a multimeter yet so there;s
Removed everything except keyboard, monitor and power cable
Took out all parts and cleaned dust out, though it wasn't too bad.
Took out CPU to check for dirt or damage though there wasn't any. Reseated
Removed graphics card hoping to vnc into it, but nothing and eventually fans get loud again
Tried booting in verbose mode but didn't work
Tried booting from OSX disk but didn't work
Couldn't run AHT from disk
Was able to get to startup manager, showed my normal startup HD but didn't show OSX disk
Target disk into it from another mac worked and HDs appear to be fine
Tried taking out secondary HD and swapping startup disk into different bay
Tried many different combinations of RAM. There are 4x256 sticks in pairs from 2 manufacturers.
With anything less than all 4 I can't even get it to chime and the power light flashes once every 4-5 seconds making me think this could be a RAM problem though there isn't much info on 4-5 flashes anywhere on the web.

Any ideas?

It's probably worth mentioning that I use this as a home server and I leave it on all the time. I've had it around 4 months and its probably been off for a max of 10 minutes in that time, added to however old it is. So there is a possibility this is a burnt out cap somewhere. I'm confident of replacing it, but finding it would probably be quite difficult so any tips or advice on that would be much appreciated.

Thanks in advance for any help
 
According to the Apple service manual,not starting up and a power light flashing every 4 to 5 seconds in indicative of not seeing the memory.If you have 4 dim slots, you should have matched PC2700 ram. With 8 slots,matched PC 3200 ram. This could be a logic board failure as well, but I would try to troubleshoot first with known good ram.
 
Hi

Thanks for the reply.

Yeah the evidence does seem to point towards ram at the moment so I'll try that. I have 4 slots in there.

It's weird that it just happened out of the blue though, there was no suggestion that something may have been wrong before now.
 
Keep in mind that the paired slots for memory are slots 2 & 3, 1 & 4 - not 1 & 2, 3 & 4.
Try just one pair (identical, same manufacturer) in slots 2 & 3.
 
Ah I wasn't aware of that.

Not sure how mine relates tho as I only have 4 slots in total

If you see this pic [not my machine]

http://farm3.static.flickr.com/2304/2085349743_f64639371a.jpg?v=0

You will see there are 2 banks of 4 slots. I only have 2 banks of 2 slots where both slots are named 1 and 2

However if I was to name these 1,2,3,4 it fits with what you have said.

If I have ram in slots 1&4 or 2&3 then I get the chime [although still hangs at the grey screen] But in any other combination of slots there is no chime and I get the single flash to signify no ram present.

I have 2 types of ram 2x256 by samsung and 2x256 by kingston. The ram was original set out as samsung in 1&2 and kingston in 3&4 is it possible for this to cause hardware damage?
 
Incorrect RAM installation won't cause damage, it just won't work properly.
Call the slots 1,2,3 and 4. Pairs will go in 2 & 3, then in 1 & 4
Use one pair (maybe Samsung) in slots 2 & 3, then try the Kingston pair in that same pair of slots. Does one of those pairs allow the Mac to boot? Replacement RAM should be fairly cheap. Your PowerMac G5 will take up to 2 pairs of 1GB, DDR PC3200 SDRAM chips.
More RAM is better, especially if you are running OS X 10.5
 
Yeah I tried the ram as you said but no luck.

If it is in that config it will chime but hang on the grey screen. If it is any other config it won't even chime and the power light flashes once every 5 seconds [no ram].

As Leopard needs 512mb to run, would the grey screen thing be usual behaviour if the system had insufficient ram?
 
No, 512MB is the minimum to install 10.5
You can't boot to the Leopard installer with less than 512MB, but if already installed, it will boot to a hard drive with Leopard already installed. It's not enough to do much of anything, and the system will be quite slow.
My suggestion is to try a known good pair (right not, you don't know if you have any good RAM). A pair of 512MB (or pair of 1GB), would allow to to try a pair in one set of slots, with enough memory that the 512MB minimum won't be an issue.
 
If the same RAM does work in 2 of the slots and is not posting in the other 2 it is more than likely the logic board. I've seen this on more than one occasion with these G5s.
 
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