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Computer reboot , strange voltage

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February 13, 2012 7:11:04 AM

Hi ,

Last few days my computer started to reboot :(  .
I started furmark and it didnt crash... well i thought it could be the cpu so i check voltage and there were some strange readings

+3.3 V V 2,88
+5 V V 5,98
+12 V V 13,94
+5 V Standby V 4,46

Could this be faulty PSU ? or something else ..... :fou: 
a c 158 ) Power supply
February 13, 2012 10:36:08 AM

Are those readings at load or idle? All of those readings are out of spec and could cause system crashes. What are your system specs?
February 13, 2012 10:52:21 AM

Looks like unload PSU by those readings.
The lable no the PSU will tell you if the listed voltages are loaded or unloaded and the tolerances. this may sound a bit daft but how good is your meter do you have a friend with another one, some meters can be put by a few points of a volt and add this to the tolerances of the PSU and the numbers could look worse then they really are.
Also even if the voltages are high you will have a pretty good mother board power regulator to sort out supply voltages for you chips.
reboots could be down to software, over heating, and bad capacitors on the mainboard.

hope this helps.
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February 13, 2012 12:21:00 PM

davidgermain said:
Looks like unload PSU by those readings.
The lable no the PSU will tell you if the listed voltages are loaded or unloaded and the tolerances. this may sound a bit daft but how good is your meter do you have a friend with another one, some meters can be put by a few points of a volt and add this to the tolerances of the PSU and the numbers could look worse then they really are.
Also even if the voltages are high you will have a pretty good mother board power regulator to sort out supply voltages for you chips.
reboots could be down to software, over heating, and bad capacitors on the mainboard.

hope this helps.


Thank you for your answer.

Those were the readings from bios. Components are not overheating i tried furmark for GPU and OCCT for CPU. The voltage deviation from default values was quite big so I suspected there was something wrong with the PSU. Will have to borrow volt meter and I'll see what the PSU is putting out.

The PSU is corsair 650W
February 13, 2012 1:25:23 PM

http://www.newegg.com/Product/Product.aspx?Item=N82E168...
i looked up a power supply and this is what i found - i will have a look when i get home as the PSU you have looks similar in quality and spec i mine.

Is it rebooting when the pc is idle - windows desktop or when doing something more intense like game's or playing a Blueray?
do you have any mods, Cooling , Overclocking, BIOS settings that change or limit fan control and CPU's speed's.
February 13, 2012 1:31:16 PM

oh Corsair PSU seem to have 5yr warranties on them so to save to much messing about give them a call or email see what they recommend. They may just RMA and replace it they you are all good. :D 
February 13, 2012 1:36:17 PM

Sorry i keep reading the Corsair website... :S

http://www.corsair.com/support/warranty

Professional Series™ Gold (Models AX1200, AX850, AX750, and AX650) have a 7 year warranty
Professional Series (Models HX450, HX650, HX750, HX850 and HX1050) have a 7 year warranty
Enthusiast Series™ V2 (Models TX650V2, TX750V2, and TX850V2) have a 5 year warranty
Enthusiast Series Modular (Models TX650M, TX750M, and TX850M) have a 5 year warranty
Gaming Series™ (Model 600G, 700G and 800G) have a 3 year warranty
Builder Series™ V2 (Models CX430V2, CX500V2, and CX600V2) have a 3 year warranty
Builder Series (Models CX430, CX500, and CX600) have a 3 year warranty
HX Series (Models HX520W, HX620, and HX1000) have a 5 year warranty
TX and VX Enthusiast Series (Models TX650, TX750, TX850, TX950, VX450, and VX550) have a 5 year warranty
CX Series (Model CX400) has a 3 year warranty
a c 158 ) Power supply
February 13, 2012 2:19:38 PM

ATX 2.2 standard states that voltage tolerance on the +12VDC, +5VDC, and +3.3VDC is +/- 5%. www.formfactors.org/developer%5Cspecs%5Catx2_2.pdf

If the voltages are being correctly reported by the BIOS, then all the voltages are greater than 10% out of specs. It would be surprising to me that the system would boot with voltages that far out of spec....much less be able to run the stress tests you mentioned with the system remaining stable.

You need to check your system logs and see what errors you are getting when the system does one of these random reboots. What changed in your system right before the reboots...software or hardware.

February 13, 2012 4:12:57 PM

Rugger said:
ATX 2.2 standard states that voltage tolerance on the +12VDC, +5VDC, and +3.3VDC is +/- 5%. www.formfactors.org/developer%5Cspecs%5Catx2_2.pdf

If the voltages are being correctly reported by the BIOS, then all the voltages are greater than 10% out of specs. It would be surprising to me that the system would boot with voltages that far out of spec....much less be able to run the stress tests you mentioned with the system remaining stable.

You need to check your system logs and see what errors you are getting when the system does one of these random reboots. What changed in your system right before the reboots...software or hardware.


Hi ,

well nothing has changed in my system. This started to happen out of nowhere. I will flash BIOS and check those readings again. Cause I was wondering before I posted on this forum how can this even work with this voltage.
I did some more tests and the strangest thing is that sometimes I can leave stress test for very long time and nothing happens next time it reboots after 2 minutes. There must be something else wrong. ( faulty motherboard maybe - It would explain the strange readings ). I have another computer at home I didnt use for a long time ( I think it has LC POWER 500W PSU inside ). Will swap PSU and check the voltage

Thank you, for quick reply
a c 158 ) Power supply
February 13, 2012 4:45:01 PM

I would check system logs for errors before going thru the trouble of swapping PSUs. A quick Google of error codes could tell you a lot about what's causing your reboots.
February 13, 2012 6:00:17 PM

Rugger said:
I would check system logs for errors before going thru the trouble of swapping PSUs. A quick Google of error codes could tell you a lot about what's causing your reboots.


Well I have checked the asus web site and there was bios update from 2009. So I have updated the bios and now the voltage deviation is acceptable.

+3.3 V 3,20
+5 V 5,22
+12 V 12,66
+5 V 5,05

The funny thing is none of those fixes seems to relate with my problem :D 

Fix chassis fan mode can't be saved after resume from S3.
Fix display priority is not correct when plugs two PCIE VGA cards.
Fixed if plug 8G memory and set "Memory Remap" as disable in BIOS, it cannot enter 64bit OS.
Update Express Gate to v1.4.4.1
update Express Gate to v1.4.6.2.

Well for now there were no reboots
a c 158 ) Power supply
February 13, 2012 6:05:31 PM

Those are reasonable voltages...and what I would expect from a Corsair PSU. The key is that you are no longer getting the random reboots. :) 
!