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PS Problem? Or Mobo?

S

steveho

n00b
Joined
Mar 31, 2014
Messages
5
I've got a strange problem that I can't resolve.
Motherboard: MSI B85-G41
Power Supply: Enermax 850W Platimax 80+ Platinum
Intel G3220 CPU and cooler
1 stick of RAM

Mobo sitting on the cardboard box, power supply sitting next to it. All I have hooked up is the 24p atx connector, and the 8p cpu connector. When I hit the power button (or more like the screw driver to the 2 pins), the cpu fan tries to turn for 1/4 second, or like 2 positions, may be 30 degrees of rotation. That's it. The power supply clicks off, like a protection relay.
The large power supply fan spins for a while until it drains some capacitor somewhere.

I grabbed another supply a Corsair CS550M, and the motherboard works. I proceeded to load up windows, etc, and stuck 2 video cards in there (280x). The supply stopped working a day later.

I grabbed an old Antec 500 Basiq supply just to see that the MOBO / CPU work. They do.
Monitor comes on. But I don't leave it on long enough to see what it says. I assume it would boot, but the Antec only has a 4 pin CPU plug, for the 8 pin socket. I don't really want to take the chance that I really need the 8-pin plug which the Antec doesn't have.

Funny thing this power supply works in the machine that had the Antec supply (old intel d945 board) . But I RMA'd the supply and got another one, same model.

It doesn't work. So here I'm thinking there's something wrong with the Motherboard. So that gets RMA'd as well.

Now the new MOBO and the new PS still don't work.

Enermax 850W works with the intel D945 board.
Antec supply works with both the MSI and the intel board.

But the Enermax 850W doesn't work with the MSI B85-G41 board. And I'm pulling my hair out.

Anyone have this experience? Is it the PS or the MOBO? Or just this particular combination?

Help?
 
You can use a 4-pin CPU plug in an 8-pin socket. There is absolutely no problem with doing that.

I've seen some strange things happen, and PSU/motherboard incompatibility for unknown reasons is one of them. If it works with other power supply/motherboard combinations, I would chalk it up as unexplained incompatibility and go with a different combination.
 
So should I change the mobo or the power supply? Either one is past the return period now. I'm thinking the mobo since that is much cheaper than the supply?
 
Were the replacements brand new components or returns/refurbs? Some refurbs aren't tested carefully, even when they're actually repaired.

Did you try the paperclip test and measure each voltage with a multimeter?

I'm at a loss, unless the Enermax 850W has plugs that don't fit quite right or are corroded (try plugging/unplugging 10 times), the timing of its Power-Good signal is off (different motherboards are affected differently by this), or the PSU requires a higher minimum load than the B85-G41 motherboard applies (unlikely, but that's what Haswell compatibility is about, although Enermax advertises zero watt compatibility)
 
I'm also at a loss. I did the paper clip test and the PS turns on. I did not measure the voltages. If I have time, I'll do that.

I don't think it is a problem with the contacts as it is extremely tight, so tight, that it is difficult to remove. No corrosion visible.

But what's the timing of the Power-Good signal? I assume the this is related to the green wire (paper clip test) somehow? This might be something that I should look into before trying other things.

The replacement mobo and ps were both new.

The other thought I had is that since this enermax is multi-rail (4 rails), perhaps the initial draw is too big for a single rail? That would mean pulling 30A from one rail though...
 
I just read up on the Power Good signal. That seems like the time when I see the cpu fan try to start spinning, about 1/2 second after turning on the power (shorting two pins on the mobo). That's when the power supply clicks off, like a protection relay. Hmmm.
 
I once had a EVGA board that did this with a Seasonic PSU. Apparently not enough power was being drawn. It was resolved by adding more devices to the board and PSU. Maybe try putting a couple of fans and drives on it and see if it makes any difference.
 
steveho said:
I'm also at a loss. I did the paper clip test and the PS turns on. I did not measure the voltages. If I have time, I'll do that.

I don't think it is a problem with the contacts as it is extremely tight, so tight, that it is difficult to remove. No corrosion visible.

But what's the timing of the Power-Good signal? I assume the this is related to the green wire (paper clip test) somehow? This might be something that I should look into before trying other things.

The replacement mobo and ps were both new.

The other thought I had is that since this enermax is multi-rail (4 rails), perhaps the initial draw is too big for a single rail? That would mean pulling 30A from one rail though...
Click to expand...

Are the contacts tight, or are just the plastic shells tight? With all of my PSUs that had to be reseated 5 times, I saw no corrosion on the pins, and most of the connectors were very tight.

The Power-Good signal is on the grey wire and is supposed to go from 0V to 5V in 0.1 to 0.5 second after all the voltages become stable. Usually the chip that controls the PSU handles this signal, probably with an external resistor and capacitor. The PSU fan can run even without a valid Power-Good signal or any output from the other voltage rails..........
 
I added a load to the platimax, a R9-280x. You can see it in the video. See if I am doing anything wrong.
Platimax with B85-G41 (not working combo)
http://youtu.be/UvPU7jlfQKc

Platimax with Intel D945 (working)
http://youtu.be/GkXnca-JznU

Antec with B85-G41 (working)
http://youtu.be/FO8hfbj4lZE

I will try to make sure connectors are individually tight, rather than the atx connector. I'll push each wire in towards the mobo to ensure connections.

Any other suggestions to try?
 
If I were you I'd test out your system with a brand new working PSU which matches the original before making that determination. Overall, I would suggest getting an EVGA PSU, they have a 10 year warranty. They have the 1000 G2 model which runs for a/b $199 on Amazon.
 
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