[SGIArtist]

Because my new O2 was quite loud, I decided to replace the PSU and CPU fans. After replacing the PSU fan the machine worked without a problem. Then I replaced the (R10K) CPU fan for a noctua NF-A6 PWM. After pushing the system board back into the machinem it's now stuck at boot with an amber led. I have to unplug the machine to shut it down and when I plug the power cord in it immediately starts the machine up. Pushing the reset button, the led turns red briefly, then becomes amber again. According to the reference manual flow chart it's a system board problem. I popped the RAM and pushed it back in. I also re-seat the CPU. Output to the serial port gives nothing.

Video:

Is there anything else I can try? I did unplug the power cable every time I removed the system board or put it back in. I also put the original CPU fan back but the problem still persists.

[weblacky]

Before anything further occurs, please confirm you were following the “remove PSU first” rule on the O2 every time you did anything to it. O2 mainboards can be killed by a charged PSU, if you remove mainboard first without popping out the PSU beforehand. There isn’t a sufficient safety if the PSU is left in place and the mainboard is removed (if the PSU still holds residual charge). Drives and video IO doesn’t seem to be a problem.

Yes, people will say I’m confused and it’s just to not leave the power cable connected to the PSU on mainboard removal. Why take any chance since we know a charged PSU can kill. I always pop the PSU before I attempt to remove the mainboard.


In terms of your behavior, I swear I’ve heard people talk about this before.

Assuming you your board isn’t damaged, I’d try the reset/force boot jumper followed by an env clear/reset. Here: https://web.archive.org/web/201804240704..._Procedure

[SGIArtist]

Thanks for your reply. No, I didn't pull out the PSU every time, since I understood that unpluggng would be enough. I tried the power on jumper trick, but the machine still just boots without vga output so, I can't get to the console.

It just feels to me like the system board isn't making a good connection, but as far as I can tell it's not possible to push the board any further into the machine.

[Jacques]

I suspect your CPU isn't properly seated on the riser cards. I've had this tons of times when I've taken my processor module out to mod it. Make sure you hold the bottom base of the system board tray under the risers, then push down gently on the heatsink to ensure the CPU contacts with the risers. Force boot jumper and it should fire up.

You should ideally look for a fan that provides around 3 mmH2O or 30Pa static pressure, 2 is a bit on the low side. The flow rate of the Noctua is fine though.

[SGIArtist]

I tried reseating the CPU once without any result. So tried again with force boot jumper, still nothing, even after clearing the jumper.
I guess somehow the system board or the CPU got damaged since the machine worked OK before :(.

[weblacky]

While what I said is by no means definitive, my mental process is it also prevents trouble when you rapidly plug in a machine, test, decide it needs work, then you quickly unplug and start pulling things again.

I’m not sure how long it takes for the PSU to really discharge. So my fear would be it takes like 1-2 minutes, and I’m excited and impatient, so right after turning it off I start disconnecting boards and such.

The PSU removal (on nearly all SGIs) forces me to wait and forces me to ensure disconnect from the system. Otherwise if I’m too fast, I might still have charge on the PSU when I go to wiggle out the mainboard. It’s just a precaution that removes several very real scenarios if I’m not paying attention.

However I’m not so hyper that I use ESD straps like SGI tells you. Unless I plan on physically touching a bunch of contacts or metal parts, I handle by grounds and plastics mostly.


If you’ve already done what you can with the CPU card reseat, visual inspect connectors, I’d either try fiddle with RAM (boot with minimal set) or pull all non-essential parts (Hdds and audio card) as well as trade minimal RAM and see if you get a new symptom.

Also I assume you tried the old fan.

[SGIArtist]

I've tried loading the system board without any ram, which gives me a blinking amber led. So at least something different. I'll try some different RAM combos.

Edit: tried multiple RAM stick combinations in first two slots, with no result.
Edit2: tried booting without the PCI slot addon, got an amber LED as well.
Edit3: put the original PSU fan back just in case, still no improvement.

There's not much I can do anymore, I'm going to have to get additional hardware for swapping to move forward.

[SGIArtist]

I got a new CPU board from a local seller. That seems to have fixed the issue. Somehow I damaged the original board when screwing in the new fan. Thanks for all the advice and help.

[Lady Serena Kitty]

I got a new CPU board from a  local seller. That seems to have fixed the issue. Somehow I damaged the original board when screwing in the new fan. Thanks for all the advice and help.

I'd be happy to take the broken board off your paws (in a few weeks).

[mftidwell]

I am responding to this old post to possibly help those new to O2's ( like me )

My O2 came with 1mb of memory, so I got more off Ebay to upgrade it. After removing the old memory and installing the "new" larger DIMMS, my O2 was stuck with the flashing amber light. Removing the "new" and putting back the old, it still flashed amber and would not boot. 

I then sprayed all the memory slots and motherboard slot with Deoxit, and wiped down the motherboard connectors with IPA. I then reinstalled four DIMMS of the "new" memory. I made sure the main board was securely pushed into the case and reattached the power cord. 

Once again I heard the happy music and the screen came to life.