Proper power supply load?

[RawDepth]

As part of my troubleshooting a DAW problem, I want to rule out the possibility of my power supply being inadequate for the machine. Here is my concern...

It has three 12 volt power rails, but nearly 20 cables/plugs coming out of it. I want to make sure that I am not overloading any single rail as far as amperage draw. The label reads as follows.

+5V = 25A
+3.3V = 25A
+12V (1) = 22A
+12V (2) = 22A
+12V (3) = 25A
-12V = 0.5A
+5VSB = 2.5A

How do I know which cables relate to which +12V power rail?
Are all drive cables on the same rail?

The power supply manual is no help.

 

[cyrano]

It's next to impossible to find out.

Best way to test, is connecting thin wires in the connectors, attaching a GOOD volt meter and monitoring the voltage while the computer is under heavy load. Start with the 3.3V rail, then the 5V. It's not very likely the 12V will give you trouble, unless you have a dozen drives or so. Usually, it's the 3.3 or 5V.

You don't even need to check the -12V, as it's only used for the RS232 port.

The numbers also look a bit exaggerated. The -12V, for example only needs 5 mA. So, 500 mA is really generous.

 

[RawDepth]

...The numbers also look a bit exaggerated. The -12V, for example only needs 5 mA. So, 500 mA is really generous.

I don't know. It is a newer Antec EarthWatt EA 650

The problem is, occasional random reboots for no reason. I really don't think it is heat related because it even does it when the machine is idle. Everything is clean and shiny inside because it is very new.

I can hear something "click" inside the machine just before it reboots. I am assuming it is something in the power supply, but I am not sure.

I only have two, (sometimes three) hard drives running. The rest of the machine is pretty standard as far as power consumption. Two old pci cards do require +12V power attached which I draw from a Molex drive connector using a "Y" adapter.

Thanks for the help.

 

[dementedchord]

I don't know. It is a newer Antec EarthWatt EA 650.

that's real good supply and should beable tp handle damn near anything... i just bought a new antec for a new project box... toms hardware did a test on supplies a few months back... their finding was seasonics were the one to have... well these are done by them... some of the corsairs too... i got a real deaal on a true power 750... as to some other thiungs to watch for... pfc...power factor correcting IIRC is good and also and 80 plus certified is another thing to watch for (bras silver gold get extra points)...

 

[RawDepth]

I've been thinking...

My old DAW did exactly the same thing. So, I built a whole new computer. (It was time to upgrade anyway.) One of the only few things in that machine that is not new is the RME pci I/O card.

Is it possible for a faulty pci card to cause a hard reboot of the machine?

 

[cyrano]

Is it possible for a faulty pci card to cause a hard reboot of the machine?

YES!

The PCI bus has a hardware bus reset line. That could be triggered because of power problems and could trigger a complete reset. I'd pull one of the PCI cards if you can work that way, and see if the problem persists. Older cards tend to draw more power...

 

[dgatwood]

I would not expect a faulty PCI card to cause a reboot. A panic, sure, but not a reboot. The only way that should be possible is if it did something insane like suddenly dead shorted +5VDC to GND. A PCI bus reset does not reboot the machine. A bus reset just means a piece of bridge logic downstream is demanding that the bus be reenumerated. It is unrelated to the reset button that reboots the machine, and to my knowledge, there's not a pin for a reboot of any sort; there's really no reason for any hardware other than the motherboard to be making those sorts of decisions.

The most likely cause of this sort of problem is either a severe overcurrent (sufficient to cause the PSU to think its output is shorted) or an actual short. Make sure there aren't any critical motherboard components that are shorting against a spacer. Make sure your hard drive's circuit board isn't shorting against anything. And so on.