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Thread ID: 35097	2003-07-02 06:21:00	CPU voltage??	Susan B (19)	Press F1

Post ID	Timestamp	Content	User
156903	2003-07-02 06:21:00	I have something bugging me that I cannot find an answer for . My mobo, a FIC VC19, Pentium 4, Socket 478, Intel 845 DDR 533 FSB has a hardware monitor with readings for the +12V & -12V , +5V and +3 . 3V & VCore . The other day I got a warning that the +12V & -12V was out of range and sure enough on the graph it had shot up from around -12 . 281 to -11 . 0 for a second or two . It has only ever done that once, the computer was doing nothing unusual and was under no stress at all . What I would like to know is what may have caused it to do that and could it have done some damage? What is the +12V & -12V actually for? And the other voltages, what are they for? All I can find are references to overclocking or CPUs running hot, etc . The other thing that I'm a bit concerned about is that the measurements are constantly changing producing a rather jagged-looking graph as shown here ( . neoburn . net/imagef1/uploaded/hardware1 . jpg" target="_blank">sal . neoburn . net) . The example in the hardware monitor's help file is a nice smooth wave like this ( . neoburn . net/imagef1/uploaded/hardware2 . jpg" target="_blank">sal . neoburn . net) - nothing like my one . Should I be worried about that?	Susan B (19)
156904	2003-07-02 06:56:00	> Should I be worried about that? No	godfather (25)
156905	2003-07-02 07:00:00	The voltages are used for different devices within the pc, but the majority of them are either 5v or 12v, the -12v and -5v are just the earth lines for these . Fluctuations in the graphs could be due to external interference (power spikes etc) or a poor psu . Try the PC on a different outlet; maybe you are sharing the circuit with something that is drawing a lot of load or causing interfernece; to this end a power conditioner could help . Also, maybe the PSU itself isn't up tot he job; there are several faq's on psu requirements that you can find on google but I would make sure your PSU is capable of sustaining the load that you are placing on it . Would I be worried about it? Probably not . Its not ideal what you describe, but I imagine millions of people run with sub-standard power supplies or on poor power without any problem; but can you be bothered with the hassle if screwy things start happening with no apparent cause?	TerryW (2183)
156906	2003-07-02 07:22:00	-12v (and -5v) is not an "earth" for +12 (+5v) . The -12v is used for such things as serial port signals which go negative and positive with respect to ground . Ground remains ground (or 0v) in all cases . If -12v was ground for +12v, then its a 24 volt supply, not a 12v one . Only if you are certain that what your on-board sensors are telling you is the truth would you get concerned . And then only if your PC was showing faults . Then consider that the software monitoring it also comes into the picture as its only "sampling" periodically, and you may not have a problem at all . Sorry, but I would only believe that waveform if an external oscilloscope showed it . The computer is not a device for measuring *accurate* temperature, voltage (or picking the winning lotto numbers) from its on-board sensors . They are "indicators" only . Comparison with calibrated instruments will usually show this . If its not broken, its not a problem . ]:) ;\	godfather (25)
156907	2003-07-05 03:21:00	If the computer works, it's OK . When smoke rises . . . it's not . The -12 is used only for the RS232 serial . . . and for that anything from about 4-15 volts would work . I don't think even the preamps on souund cards use balanced 12V . The -5 is totally "historic" . It was on early computers because some dynamic RAM (and some EPROMs and ROMs -- BIOS/BASIC) used -5V .	Graham L (2)
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