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AX750 overheating?

L

laukinisvilkas

Weaksauce
Joined
Dec 9, 2009
Messages
77
Hi, before I begin I have no warranty (its still only 1 year old).
So it's summer here (Europe, the room temperature is at around 27-30 degrees Celcius) and my PC suddenly started to reboot without any bsod, it's just a reboot without any hardlock or anything like that. Well I scratched and first thought it was PSU but wanted to believe something was short-circuiting since I had many peripherals connected. It did not help :(

Long story short, when heat once again came (now) PSU once again started to reboot so I associated the two - the heat and the rebooting.

Lets just say the cooling of motherboard, cpu gpu and all my hard drives is not the problem...

The problem which baffled me is that even when idle it could have rebooted at random intervals (so even at around 100W).

The thing I see right now as THE problem is that the fan of AX750 never starts to spin. I have 3770k at 1.25V @ 4.5 Ghz running prime blend 8GB ram used and GTX 670 overclocked 680 PCB running MSI kombustor using ~110% power and it should be at the very least 350-400W and the AX750 Fan just does not start to spin. Right now I my own fan blowing the air through the internals and rebooting stopped.

The thing is I see that the fan should be aware of both temperature of PSU internal components and power consumption but it is not. Since I have no warranty I plan to disassemble the PSU to test if the fan is faulty but before I begin I want to ask if my thoughts about fan failing are correct? Or may it be the controller in the PSU itself?

Thank you!
 
How is it positioned in your case? Is it sitting with the fan grill down or up?
 
It was grill down since its the Fractal Design Define R4 case. But now its the grill up obviously since I put a 120mm noctua fan on top of it to cool off PSU.

Btw I can say that I have no luck with ax750 because a year ago I started topic http://hardforum.com/showthread.php?t=1692977&highlight= , and it actualy was a bad PSU, bacause back then I still had a contact at the supply center and he said they had a defective batch of ax750, so I had mine exchanged but he couldnt tell if it was defective in any way and it wasnt for almost a year...

Edit: now that I think about it, a year ago I definetely remember psu fan spining when pc wasnt idling.
 
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Remove the overclock and overvolt, see if its now stable, including under under load
 
Yeah that was the first thing I did, didnt help one bit. Once, at default settings, pc rebooted when in bios :)

The thing is, today the heat came (again) and PC once again started to reboot once every ~30 minutes (it was as stable as it can get for a week, but it was by far cooler at home, at around 20 degrees, now it is around 30 and that is when I thought to check if PSU fan is spinning, because I was gaming in long sessions for a whole week and thought maybe it was my home electric circuitry which was at fault since I (ironically) moved my pc from balcony (hot) to room (cool) and problem went away for a whole week)). Sorry for crying here but I never had much luck when it comes to reliability of electronic equipment (how my creative gigaworks s750 still works after 3 years in service is astonishing me, maybe the fan on the radiator helps :) ).
 
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Rebuild the hardware and clean the connectors/blow out dust, in case there is a bad connection.
Build it outside the case, in case a piece of metal has worked its way under the motherboard, or you have another form of short circuit.

If you can borrow another PSU to test with, that may help you.

Something I had a problem with.
Make sure all the connectors to the PSU are very well fitted.
I was having graphics card issues, refitting the cable to the PSU sorted them out.
 
Thank you, definetely will clean it tomorrow, maybe I will also remove my "extra" fan on top of PSU just for testing if heat is the problem :confused:
If it continues I will take my old trusty chieftec CFT-750-14CS from my parents place where my all previous builds eternally rest, its just a long drive back home just for PSU. And all my friends use laptops, because they are definitely enough for their needs.
 
Random reboots are rarely a sign of PSU failure. Maybe it's some RAM that doesn't like running at higher temps?

Overtemp protection on PSUs shut them down, they don't cause a restart, since a restart does absolutely nothing to lower temps on a PSU.

In any case, the only definitive way to figure out is to swap with known working good parts, as electronics can interact in very weird ways.
 
He is using a modular PSU, a bad connection at either end of a power lead can cause a reboot.
Even though this type of issue is rare, it should be checked and is easy to do.
 
Edit: Also cleaned everything inside psu and contacts but there were not much dust inside since I live in pretty dust free environment right now.
Since the heat went away I cannot in any way make pc to turn off by itself (at least I made conclusion that it is caused by heat..).
I taken the fan from ax750 and connected it to my fan controller and it definitely works. Now when I have time after work, will test if the fan controller in PSU is faulty because if it will not work after an hour under load of prime blend and MSI kombustor, then it is definetely faulty (previously tested only 10 minutes, bad on my part...).

The ram overheating is actually very good idea, because I have P8Z77-V PRO and Noctua nh-d14 is blocking all 4 ram slots so I had to get ram with very short heatsinks (the ram is 1.5V kingston 1600 Mhz ram with compact blue heatsinks is the only component I cheaped out on)... dunno how to stress it any differently than with prime blend max ram?

Thank you, will post solution to my problem if I find such without changing half of PC (and I had such issue with my very first build 10 years ago, had to change whole pc).
 
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Try HCI Memtest. It'll stress out the RAM.

Did you seriously take apart your AX750? You just voided any warranty you had...
 
Well the fan spin again...
So I returned from work, reconnected the original San Ace fan, started to run both kombustor and prime (340 W from the wall, have EU version of kill-a-watt) and after less than a minute the fan started to spin... Then tested prime alone (200 W) and again after ~10-20 seconds fan started to spin... Was it some loose contact or dust I have no idea but it now spins and it didnt before under the same tests.
I also tested ram for about 2 hours, HCI Memtest, 5 instances (2gb per instance), to 115% coverage without errors and those ram sticks got hot (was only able to touch the last ram stick because of cooler blocking all the rest).
I'm out of ideas since pc is still going strong since saturday. So I atribute it to either the PSU fan (because on saturday, after few quick random restarts I put a fan to blow air through PSU and restarts stopped since then)or the ram sticks which will get 30mm fan if I get any more restarts.
Also I'm pretty sure that before the disassembly of PSU the fan never span under any circumstances since I was gaming a whole lot and I never saw it spinning, and I was playing metro which pulls well above 200W from the wall.
I just hope that I will be, for once, able to solve this without any monetary investments on my part :(
Once again, thank you all for your help.
 
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I think 2 hours of memtest is not sufficient to test the ram. My ram passed the 5 hours of memtest but failed on 10 hours of memtest. So just try to do at least 12 hours I would say
 
I think after 2 weeks without any random reboots I can firmly say it was the PSU fan problem (maybie some dust got in the way..). Now it spins even at 100 W load if it is hot day...
 
The AX series shuts its fan down if it doesn't believe itself to be hot enough to need the fan.
 
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