Is it safe to assume this M2-ATX is bad?

l33der · 05-17-2008, 09:51 PM

I bought a M2-ATX new(I hope it was new anyway) last month from idotpc and finally got around to installing it today. I'm using a full sized ATX computer (Athlon XP 1800+, GeForce ti 200, Soyo Dragon+ mobo) which powers on just fine with the use of a regular PSU.
I plug in the M2 on the other hand, and I get power to the LED on the board, and the fans spin EVER so slightly. This repeats, over and over - powers off, powers on LED, spins fans a little, powers off. I figured it had something to do with my switch, so I put it in dumb PSU mode and tried to manually trigger power by shorting the header on the board and it behaved similarly - it turned on the LED, fans started to spin, but couldn't. Instead of turning off and on though, it just makes the fans flick just a little. No video, no beeps, nothing.
I thought it might be a power draw issue, and just to be on the safe side I hooked it up to a completely naked motherboard with just a fan plugged in, and it did the exact same thing.

Should I assume that I have to just get a new PSU? I like the features of the M2, except it just doesn't work. I don't think I'm having a power draw issue, so throwing more money (Opus) at the problem doesn't seem like a good solution. I see a lot of threads complaining about M2s, but I also see a lot of praise, so I feel like maybe I'm just unlucky. Idotpc's phone RMA thing hung up on me, but it is Saturday, so I'll try again on Monday.

2k1Toaster · 05-18-2008, 12:08 AM

Could it be you are overloading it? Have you checked the maximum current draw on all rails?

l33der · 05-18-2008, 12:21 AM

If I'm overloading it with an empty motherboard with nothing but a small northbridge fan, then I don't want this product. According to the big thread, the 12v rail puts out 96w and the maximum dissipation on my cpu is 66w, I don't know much about calculating the total draw - but a completely bare motherboard save for a fan should not be too much for this PSU, unless I completely misunderstood the power of this thing.

Trench · 05-18-2008, 02:01 AM

Make sure you have large enough wires powering the M2, and if you are using a battery make sure it is powerful enough, or if you are using a 120VAC to 12VDC converter of some sort, make sure it is powerful enough.

I had the same exact issue as you when I was first piecing everything together. The reason ended up being caused because I had the M2-ATX powering off the tiny Floppy drive power wires from an old Power Supply. I moved the power leads to the larger lines (for CD drives/Hard drives) and it powered right up.

Hope this helps,
Dustin

l33der · 05-18-2008, 05:43 AM

I don't know if the battery might not be powerful enough (whatever comes stock with a 2004 Honda Civic LX) but I am running it off of a standard computer power cable(I hooked up a connector for one to make it easier to remove the computer) plugged into a 16 gauge wire extension cable, so I don't think it's wire size that's an issue. I'll see if I can find a 120VAC to 12VDC converter to try it, though I don't think I have one.

Trench · 05-18-2008, 07:06 AM

16GA is pretty tiny, that could be your problem. You should be using 12GA, if not 10GA.
If all you have laying about is 16GA and you are impatient like me, then just double up the leads temporarily in order to test it out.

l33der · 05-18-2008, 09:03 PM

You just saved me a load of grief. It wasn't the 16GA extension cable, that's fine. It was actually the computer power cable I was running to the box that is apparently smaller than that, and was causing the problem. I ran some 16GA between the box and computer and it turned on just fine. So now I just need to find a computer power cable 16GA or better.
Thanks a lot, you saved me returning this thing for nothing.

Trench · 05-18-2008, 09:13 PM

Very good to hear!

FusionFanatic · 05-18-2008, 09:57 PM

every standard 3-pin computer/monitor power cable I've seen uses 18awg wire. I'm sure you can find a 16awg cable somewhere, but 16awg is still not big enough. there are two factors to consider when choosing a wire gauge; ampacity and voltage-drop...

-ampacity is the amount of current the wire can handle without heating up and melting it's insulation off. if you exceed a wire's ampacity, the melting insulation CAN and WILL start a fire!

-voltage-drop is the change in voltage between the power source (car battery) and load (M2-ATX). excessive voltage-drop will prevent a device from operating properly (which is probably why your M2-ATX would not turn on with the thinner wire)

-both factors are determined by the wire's resistance. the resistance of the wire will create a voltage drop at the other end, the resistance is determined by the wire's thickness and length.

in your case, your M2-ATX wouldn't turn on with 18awg wire, but it turned on with a [slightly thicker] 16awg wire. that means that it barely got enough power to start up. once the CPU usage increases, more power will be demanded from the PSU, which will demand more power from the car battery. chances are the ~20ft run of 16awg wire will not be able to provide the PSU with enough "juice" to operate properly. you need a much thicker wire to prevent an excessive voltage-drop over the ~20ft run into your trunk. I run 10awg wire to mine

NOTE: your ground wire needs to be as thick as your power wire, and it should be connected to a clean metal panel (unpainted, uncoated). a bad ground will also cause the problems you are having, but your wire gauge issue needs to be corrected first.

good luck

l33der · 05-18-2008, 10:06 PM

Well, I'm a software guy, so I have no room to argue with anyone who has successfully done this. I will take your advice and move over to 10, it's just going to mean I have to run the wire again from the hood. I'd rather do it right this time than do it three times, though. I guess I'll abandon the idea of using a computer power cable to run from the box I installed to the computer.
Or, I could always make one with 10 gauge myself, I suppose. I did find some at 16, and even one at 14, but none at 10.

Thanks for the advice.