G5 Quad doesn't POST. Checkstop led blinks

[pshirshov]

I’m playing with a Quad Core PowerMac G5 (A1117). So far everything was fine, I’ve reworked all the thermals and the machine worked well for more than a week under high load, compiling non-stop.
Today I’ve turned it off and after several hours tried to turn on. But it doesn’t POST anymore - checkstop led (led #7) blinks twice after power on, then waits, then blinks twice again. I’ve tried to pull out the RAM and graphics card - no change. Tried to power on without CPU module at all - well, as expected it turns on CPU leds.

Video:

Would be grateful for any hints what may it mean.

There were no leaks from the system. So I'm afraid that some solder may get cracked due to normal thermal shrinking/expansion... But it still would be cool if I can decode the leds.

 

[Eriamjh1138@DAN]

Took me two shakes to find this:

All codes

SOLVED: Power light blinks twice, fans high - Power Mac G5

The fans kick into high by default when a temp sensor fails to keep from cooking the CPU or other components like a GPU. You have damaged RAM, and possibly other problems. • 2 Flashes: No RAM is installed or detected (could be bad RAM). • 3 Flashes: Incompatible RAM types are installed. • 4... -...

www.ifixit.com

So, two flashes then two flashes, is either bad ram or no ram.

So.. ram. Try reseating it..

 

[pshirshov]

Nope, I've figured out what was it. CPU B passed away. The system posts without it. Still wondering why did it happen...

That post was about power led codes, though in my case I got checkstop blinks. There are no explanations for checkstop led (led #7) codes - according to all the manuals it can be either on or off.

Though now I figured out that double blink means that cpu b is dead and single blink means that cpu a is dead (when I put cpu b into slot a it started blinking once).

 

[defjam]

Nope, I've figured out what was it. CPU B passed away. The system posts without it. Still wondering why did it happen...

That post was about power led codes, though in my case I got checkstop blinks. There are no explanations for checkstop led (led #7) codes - according to all the manuals it can be either on or off.

Though now I figured out that double blink means that cpu b is dead and single blink means that cpu a is dead (when I put cpu b into slot a it started blinking once).

It's an old system and things start to fail with age. Or things get wonky when you mess with them. I just experienced an issue with my dual 2.3GHz G5 system. Except for a bad memory slot it was working fine. I replaced the system board with a replacement. Unfortunately the replacement didn't work (though it was pulled from a working system) so I reinstalled the original system board. Upon doing so I had problems with it. Just resolved it a few days ago but not sure what the problem was (there's a thread in this forum if you want the details). It's old and finicky. Ironically I almost replaced with with a quad G5 which I could have picked up inexpensively but decided against it due to the liquid cooling issues. I am avoiding any liquid cooled G5 which means I unfortunately will miss out on the quad.

 

[pshirshov]

I understand but the reasons of the failure are interesting. Like it may be a crack on one of the conductive tracks on the card, or broken soldering. Or something is wrong with the crystal. Or I overtightened the screws and damaged the crystal or the board. But anyway, that's impossible to find out...

 

[Eriamjh1138@DAN]

We all mourn the passing of CPU B.

 

[pshirshov]

By the way, I've found out that 2.5 gHz 630-7419 CPU card seems to be interchangeable with 2.3 gHz 630-7418 - I was unable to find 630-7419 on ebay but found cheap broken 2.3 gHz Dual in a local shop, tried to put its CPU card into my Quad - and it worked without a problem and calibration was not required. The system reports 2.5 gHz frequency. Handles load without a problem (3 x FullHD h264 videos are playing smoothly).

From what I can understand 630-7418 and 630-7419 are completely identical - 630-7418 seem to have the same CPU and all the components looks exactly the same - and the only difference between them were small plastic inserts in screw holes which I had to remove to mount it onto my LCS assembly.

 

[ediflorianus]

L.E. Sorry I seen your last post only after posting.


Check everything , change CMOS battery , reset PRM buton after all is put right in (check all components 3 times) . check CPU paste before reassembly. Power ON . stlil blinking , power off reset PRM (use to be next to memory in my G5). Power ON. If all else fail , pull plug press button remove CMOS battery and switch CPU places(0to1&1to0). If its a whater cooled version clean contacts with dry contact cleaner. Nothing works check capacitors on board and in PSU. You can use WD40& diskbrake cleaner as last-last resort.

 

[Eriamjh1138@DAN]

You can use WD40& diskbrake cleaner as last-last resort.

Sorry to ask, but is this for cleaning contacts? I’ve never heard of using WD or brake cleaner on a PCB (But I am not a super-computer repair person).