Optiplex 790 SFF shuts down after 10 minutes - PSU fan problem?
I have an Optiplex 790 i5 small form factor, 6? years old, which has started to shutdown after 5-10 minutes of running. It has a fan cooling the CPU and onboard video heat sinks; a case fan at the front of the box; a fan in the PSU box.
I tried the usual actions: clean dust out of everything; clean white paste off CPU and video chip and reapply new paste; check all fans running; disconnect non-essential devices ie add-on video card, DVD drive, second HD. Shutdown problem continued. BIOS diagnostics ran and reported everything ok. The test button at the back of the PSU gives a green OK light, and all fans spin. PC does not shutdown when PC has power but PSU is not connected to motherboard. Program CPUID Hardward Monitor shows reported temperatures within limits.
In view of all that, I thought the PSU might have a heating problem. I placed a spare 12V case fan near the air inlet to the PSU box, to increase air flow. That enabled the PC to run for hours.
So then I replaced the 12V fan inside the PSU box. The PC still shutdown after 10 min.
So it seems like the PSU fan alone is not delivering enough air to cool the PSU, even though it was ok in the past. So I am wondering - is there a heat sensor in the PSU which is failing or out of spec? Any other ideas on this problem and its solution? Thanks.
I can buy a used replacement PSU (exactly the same part ID) on ebay for about $40.
I tried the usual actions: clean dust out of everything; clean white paste off CPU and video chip and reapply new paste; check all fans running; disconnect non-essential devices ie add-on video card, DVD drive, second HD. Shutdown problem continued. BIOS diagnostics ran and reported everything ok. The test button at the back of the PSU gives a green OK light, and all fans spin. PC does not shutdown when PC has power but PSU is not connected to motherboard. Program CPUID Hardward Monitor shows reported temperatures within limits.
In view of all that, I thought the PSU might have a heating problem. I placed a spare 12V case fan near the air inlet to the PSU box, to increase air flow. That enabled the PC to run for hours.
So then I replaced the 12V fan inside the PSU box. The PC still shutdown after 10 min.
So it seems like the PSU fan alone is not delivering enough air to cool the PSU, even though it was ok in the past. So I am wondering - is there a heat sensor in the PSU which is failing or out of spec? Any other ideas on this problem and its solution? Thanks.
I can buy a used replacement PSU (exactly the same part ID) on ebay for about $40.
ASKER
Thanks for your thoughts. The WinLogs/System mainly shows Info items. There is also an xCritical Kernel-Power which says:
"The system has rebooted without cleanly shutting down first. This error could be caused if the system stopped responding, crashed, or lost power unexpectedly."
And also a !Error which says:
"The previous system shutdown at 3:44:06 PM on 6/9/2018 was unexpected."
I do not have the depth of technical knowledge to say whether there is anything else of relevance in the logs.
If GPO means Group Policy Object, I do not know the significance of that. This PC is standalone and was setup with a clean install of Win 10.
I have scanned with Avast and Malwarebytes and no virus problems are found.
It is notable that, after an unintended shutdown, the PC will not immediately restart after the AC power is then turned off and then on again. A 10-15 min wait is needed. It seems like something in the PSU needs to cool down or reset before the PC will boot up again. If the PC is shutdown properly (Win Power Off menu), it will restart immediately when powered up.
The PC continues to run ok for long periods if I have the external case fan blowing air into the front of the PC.
Any other ideas appreciated.
"The system has rebooted without cleanly shutting down first. This error could be caused if the system stopped responding, crashed, or lost power unexpectedly."
And also a !Error which says:
"The previous system shutdown at 3:44:06 PM on 6/9/2018 was unexpected."
I do not have the depth of technical knowledge to say whether there is anything else of relevance in the logs.
If GPO means Group Policy Object, I do not know the significance of that. This PC is standalone and was setup with a clean install of Win 10.
I have scanned with Avast and Malwarebytes and no virus problems are found.
It is notable that, after an unintended shutdown, the PC will not immediately restart after the AC power is then turned off and then on again. A 10-15 min wait is needed. It seems like something in the PSU needs to cool down or reset before the PC will boot up again. If the PC is shutdown properly (Win Power Off menu), it will restart immediately when powered up.
The PC continues to run ok for long periods if I have the external case fan blowing air into the front of the PC.
Any other ideas appreciated.
you can renew the heatpaste on cpu, and video chip
run also Speedfan for monitoring temps : http://www.almico.com/speedfan.php
run also Speedfan for monitoring temps : http://www.almico.com/speedfan.php
ASKER
Thanks. I have cleaned the old heatpaste from the CPU and video chips, applied new paste and checked the heat sink is properly clamped down.
I have run Speedfan and CPUIDHardware monitor to check temps. Temps are always at reasonable values. BIOS diagnostics also reports everything ok incl temps.
Placing a fan in front of the case to drive more air through the PSU continues to keep the PC running ok. So looks to me like the problem is related to temperature in the PSU after running for a time. I'll probably need to replace the PSU, unless I can find out what component(s) in it might be causing a heat problem (which is fixed by having a greater fan airflow).
Further research reveals that many users have had problems with Dell Optiplex PC PSUs, eg see:
https://www.badcaps.net/forum/showthread.php?t=40726
https://community.spiceworks.com/topic/213741-optiplex-790-psu-failure-common
https://www.dell.com/community/Desktops-General/Issues-with-Optiplex-790-SFF-240-watt-power-supplys/m-p/3836938
These people even remanufacture these PSUs with better caps to address the apparently well known PSU overheat issue:
https://circlecomputer.com/products/optiplex-h240as-00-dell790
I have run Speedfan and CPUIDHardware monitor to check temps. Temps are always at reasonable values. BIOS diagnostics also reports everything ok incl temps.
Placing a fan in front of the case to drive more air through the PSU continues to keep the PC running ok. So looks to me like the problem is related to temperature in the PSU after running for a time. I'll probably need to replace the PSU, unless I can find out what component(s) in it might be causing a heat problem (which is fixed by having a greater fan airflow).
Further research reveals that many users have had problems with Dell Optiplex PC PSUs, eg see:
https://www.badcaps.net/forum/showthread.php?t=40726
https://community.spiceworks.com/topic/213741-optiplex-790-psu-failure-common
https://www.dell.com/community/Desktops-General/Issues-with-Optiplex-790-SFF-240-watt-power-supplys/m-p/3836938
These people even remanufacture these PSUs with better caps to address the apparently well known PSU overheat issue:
https://circlecomputer.com/products/optiplex-h240as-00-dell790
ASKER CERTIFIED SOLUTION
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ASKER
The power calculator recommends a 240W PSU - which is the rating of the PSU in it. However no extra 20W margin.
The PSU fan runs ok. It has only two power wires (no speed control wire), so presumably runs full speed at 12V all the time.
CPUIDHWMonitor shows all reported voltages, temps and power levels within reasonable limits.
The event viewer shows "unexpected shutdown" message when the PC turns itself off, but no other problem messages I can recognise.
I have found more reports of problems with this PSU model, which seems to have some dubious caps in it. As my PC was running without problems until recently, I assume some component(s) are having heat problems when provided with only normal PSU fan flow, but the extra outside case fan blowing more air in is enough to keep things cool (for now).
I could buy a replacement used PSU but it might not be a good long term investment. If I can get a replacement cheap enough, I'd try it. Otherwise, I'll keep going with my extra fan and see what happens. The PSU might fail completely eventually, even with extra fan breeze.
The PSU fan runs ok. It has only two power wires (no speed control wire), so presumably runs full speed at 12V all the time.
CPUIDHWMonitor shows all reported voltages, temps and power levels within reasonable limits.
The event viewer shows "unexpected shutdown" message when the PC turns itself off, but no other problem messages I can recognise.
I have found more reports of problems with this PSU model, which seems to have some dubious caps in it. As my PC was running without problems until recently, I assume some component(s) are having heat problems when provided with only normal PSU fan flow, but the extra outside case fan blowing more air in is enough to keep things cool (for now).
I could buy a replacement used PSU but it might not be a good long term investment. If I can get a replacement cheap enough, I'd try it. Otherwise, I'll keep going with my extra fan and see what happens. The PSU might fail completely eventually, even with extra fan breeze.
you can also look in the PSU for swollen, or leaking capacitors - and replace them; here an example of how they might look :
ASKER
I looked for visibly faulty electrolytic caps when I originally opened the PSU case. None visible, although a faulty electro cap might not show swelling etc. Comments on repairs of this PSU often say problems start with a high voltage ceramic cap failing, because the original ones did not have a high enough voltage rating (original was 1kV and 2-3kV needed, it seems). There is then a consequent cascade of other component failures. So I doubt repair of this PSU is economical or within my abilities - not to mention availability of repair components.
So at this stage I am continuing with the extra fan, monitoring developments and watching for a cheap replacement PSU from a pulled down PC.
So at this stage I am continuing with the extra fan, monitoring developments and watching for a cheap replacement PSU from a pulled down PC.
i don't know if replacing th PS is an option ?
ASKER
Used examples of that PSU are available on ebay eg:
https://www.ebay.com.au/itm/DELL-Optiplex-390-790-990-SFF-POWER-SUPPLY-H240AS-00-240watt/253693448695?hash=item3b114ed1f7:g:df0AAOSw~u5a2cmA
However it might not be a good option long term, as a replacement PSU might also develop problems. That PSU seems to have a poor reputation for reliability.
https://www.ebay.com.au/itm/DELL-Optiplex-390-790-990-SFF-POWER-SUPPLY-H240AS-00-240watt/253693448695?hash=item3b114ed1f7:g:df0AAOSw~u5a2cmA
However it might not be a good option long term, as a replacement PSU might also develop problems. That PSU seems to have a poor reputation for reliability.
keyword in your post is MIGHT
so we dont come out of the house because the air might fall down on us?
at that price, it seems a small risk - and check if you can get it confirmed that it works
i believe normally there's a 1 month return option
so we dont come out of the house because the air might fall down on us?
at that price, it seems a small risk - and check if you can get it confirmed that it works
i believe normally there's a 1 month return option
ASKER
Thanks again for yr thoughts. I'll look for a cheap replacement PSU. I don't think repair of the the current one is feasible.
No comment has been added to this question in more than 21 days, so it is now classified as abandoned.
I have recommended this question be closed as follows:
Accept: nobus (https:#a42593345)
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I have recommended this question be closed as follows:
Accept: nobus (https:#a42593345)
If you feel this question should be closed differently, post an objection and the moderators will review all objections and close it as they feel fit. If no one objects, this question will be closed automatically the way described above.
FireRunt
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is there no GPO active ?
it could be a software or virus also