Power supply pin voltages over the "12v,3.3v,5v" specifications

Kbowers · Jul 21, 2016

So I've been having problems with my first build... Go figure
Before I go into too much detail, let me give you my specs.
Case: CoolerMaster HAF 912
MoBo: MSI B85-G43
Chipset: i5-4690 LGA 1150 (mobo compatible I double-checked MSI)
Ram: Corsair vengeance pro DDR3, 2400MHz and 16Gb
PSU: Thermaltake Smart 750w 80 plus bronze
HDD:WD 1Tb with Win 10 on it.

And now to my problem.
I "finished" my rig around Monday... And when I plugged everything in- moment of glory!... No boot no screen. So I delved into the help forums here for help. I really liked JSCs breadboarding technique (thanks man!! ) so started with just the chipset fan, chip, mobo and PSU (Case speaker too), and guess what! No beep. :/
Fans and lights turned on, no POST and nothing else...
So back to fixing the problem! I had made guesses that the PSU was the problem. I tried the paper clip test, and it worked, but as people have pointed out it doesn't guarantee that the PSU works.
So I busted out the multimeter and my mobo guide (that manual MSI sends out with all the fancy illustrations of the ports and what they do) and got some pretty strange readings...
(Side rant, the PSU model I got had no colored cables so I had to use my MSI manual to figure out what is what... Ugh)

So for every 12v cable, I got a real life voltage reading of 19v- 20v. Every ideal 5v was about 8.36 and every 3.3v was really 5.5....
So here is my real question. Is the power supply the broken part? Or is it the motherboard? Would that over..abundance (yeah overabundance) of voltage damage the motherboard into breaking?
I just need to know what to send back to the MFG under warrantee or if it's my fault something broke...

Thank you for your time in advance!

clutchc · Jul 21, 2016

Those voltages are WAY out of line. +/- 5% is the normal accepted variation. But are you sure you are reading between the correct wires since they are not color coded? If you are pretty sure you are correct, then the PSU is defective. If you aren't sure, you can pick one of these up fairly cheap to verify your reading: https://www.amazon.com/HDE-Power-Supply-Tester-PCI-E/dp/B005UZHB6G/ref=sr_1_1?s=pc&ie=UTF8&qid=1469158608&sr=1-1&keywords=psu+tester

Kbowers · Jul 22, 2016

I'm confident I read the right voltage between the wires. It took a few confusing minutes to orient myself but I am certain the pins are correct.
I do have a slight concern my multimeter may have been "knocked out of alignment" with a few gadgetry mishaps (involving shorting a security system power feed... But that's a different story). I am going to get another multimeter (easy and cheap and quick to obtain- I have a time constraint for this build) and if the readings are again above the limit, I'll send back the PSU.
What are the chances its damaged the motherboard? Would that explain the fans spinning and lights turning on but the more sensitive electronics not activating? The fan and lights don't need/have overload protection?

Thank you for all of your help!

maxwellmelon · Jul 22, 2016

Kbowers :

well its easy to check if its reading 12 volts correctly if there's a car battery you can CHECK SAFELY(if you don't know anything about cars don't mess with this test!!!!!!!!!!!!!!!!!). a car battery should show 12-12.5 volts with the engine off.

you can also just check it with a nine volt battery (should read 9 to 9.3 on a new one) if it reads a nine volt battery fine then your meter is deffently working correctly.

clutchc · Jul 22, 2016

Kbowers :

I guess it is possible to damage the board with the high voltages the PSU was supposedly supplying. But it would depend on the over-voltage protection (if any) incorporated into the board.

giantbucket · Jul 22, 2016

um, you're testing a no-load condition, so the regulator isn't really doing anything other than letting the voltage float up. put a load on it and then poke it with the multimeter.

Kbowers · Jul 24, 2016

sorry! I forgot to mention that- I had a load on... very small though. I put on a MOLEX case fan. And as it turns out, my multimeter was wrong.... I went in and used a different multimeter and it turns out that the PSU is operating on the correct voltages. So I'm going to assume its a motherboard malfunction. unless you guys feel otherwise, I will begin contacting MSI (or however it works to fix a Mobo.). Thank you everybody!

Search

Power supply pin voltages over the "12v,3.3v,5v" specifications

Kbowers

Commendable

clutchc

clutchc

Titan

Kbowers

Commendable

maxwellmelon

Splendid

clutchc

Titan

giantbucket

Dignified

Kbowers

Commendable

TRENDING THREADS

Latest posts

Moderators online

Share this page