Second PSU Burns up on 24-pin

Alright guys, one of my friends' systems is having an issue. Here's what he's got:
Asus P7P55D Pro Motherboard
Corsair 850TX PSU
i5 750
Dual 4890's
8GB of G.Skill memory

Some hard disks and drives and whatever.

He's on his second PSU after he discovered that the 2 of the pins on the supply were burnt together. He said he encountered this after smelling burning while playing BFBC2. This was after about 5 months of use of the machine. He replaced the supply with the same model, and kept on running the machine.
Now, just today, about 10 months after being built, the second supply has burned up. This time, though, it was noticed when the machine wouldn't turn on today - it was working fine last night, and was shut off during the night.

So, I'm inclined to say the board is the issue here, since it's unlikely two power supplies burn up the same pins. There doesn't appear to be any evidence of shorting on or around the board or on any of the empty supply connectors. However...the burn marks on the connector are only on the top where it meets the supply connector, and the wiring is melted off on the supply's connector; it doesn't physically look like the board is at fault.

We're going to refurbish the connector and test the supply in another machine, but while we do, I just figured we'd get some second opinions in here. Any ideas/ similar experiences? He'd really rather not replace both parts.

Pictures here:
8 answers Last reply Best Answer
More about second burns
  1. I would say a short on the board. Looks like pins 10 and 11 that is both +12 volt wires. Bad voltage regulator running of the 12volts could be doing this.
  2. Best answer
    I have seen this problem many times before, the board is drawing lots of current through each pin and any contamination on the pins causes the contact resistance to be higher which causes the pin to get hot which causes oxidization which causes the pin to get hotter and more oxidization until it burns out. By replacing the power supply you have fixed half of the problem but not the cause. As the burn up on the connector is so bad in this case only the replacement of the connector on both the power supply and the motherboard will cure the problem. There is no other fault with the motherboard so if you are good with a soldering iron then give it a try and replace the connector otherwise you need to replace both the power supply and the motherboard. This is the reason that the extra 4 pin connector was introduced to help stop this from happening. (You did connect the 4 pin connector didn’t you?)
  3. Eventually replaced the PSU and the board - and a few months down the road, same problem starting to happen again.
  4. could be bad contact between the psu plug and board socket
  5. Well, I took the heatsink off and found that there was some kind of...stuff...on the bottom of the CPU. I've cleaned it off and I'm now breadboarding the machine.
  6. ^The Thermal Paste Needs to remain between the CPU and Heatsink. (Clean it up under tho)^

    I just got the Burnt 4 Pin connector , and several of my 24 pins are sooted from heat and smoke.

    All started by smelling something, I cleaned The PSU and but didnt find the faulty pins, actually took the enclosure off to clean the power supply drained all the power but never bothered with disconnecting it.

    I began to disconnect what I thought were faulty fans, smelling smoke pass through them gave the illusion the smoker deluxe smell was coming from the fans.

    30 mins I began to notice crashing and rebooted 2 times to windows screen.

    I gave 1 look at my Nspire 430 watt Diagnosed it as faulty (NOTE PINS burnt pins) and thought how it had been there thru several builds. (Then I reconized it as the 8 year old peice of crap that blew my Motherboard.)

    I had 2 scrap MOBOS with 4 pin connectors, I replaced the 4 pin connector and powersupply.
    The trick is to pull the scrap part first, provides practice, Disconnect by heating 2 pins at a time and working the 4 pin off like a tooth. Sodering reqired for removal.

    I got the PSU in there now and ive been online for an hour no problems replaced it with a DELL from an XPS Solid as a brick

    I did reconize several times that I might have had a faulty PSU by how my 12v devices reacted. Harddrives would burst never a solid stream of data.

    My UsB speakers actually under certain settings pick up motherboard frequencys while not unnormal u can monitor the activity by listening, I was getting unrythmic burst and hanging.

    My GPU was acting slower than usual and when I had the 7800Gs A capcitor would chirp at the oddest unused times (Nvidias intentional design to warn me not all was well.)

    There are allot of ways to test the PSU I actually have a 24Pin tester from dell somewere.

    But they can as I learned DAMAGE any component attatched them. So I want to close it up with what to look at in a PSU When making a selection. Short electrical class first Wattage, Voltage, amperage and resistance 4 diffent things.

    Many People select a PSU from the wattage alone which is WRONG , worse they only look at peak wattage.

    Your Ideal powersupply will have an
    1) Internal fan
    2) Supply connections for all your components
    3) Should never be under 350watt
    4) Support multiple 12VOLT rails with at least 17 amps on each....Balance the load for longevity and perfomace DONT PUT ALL THE HD, BURNERS AND GPU ON ONE RAIL

    5)The average power supply should have wheight, Its a testiment to its design,If I was forced to chose between 2 models of exact rating ide choose the heavyer one.

    12volts x 17amps = 306watts peak for that rail < even if it is a 500watt PSU your 12v Rail is only a portion of the power balance it up!
  7. Best answer selected by frozenlead.
  8. The issue was actually the pin oxidation. I had a 24-pin extender on hand, and I ground off the oxidation with a dremel tool, and then put the extender in place to keep the two separated. It's been working fine for several months now. The unit was a very good Corsair 850TX, so I wasn't really concerned with the quality of the actual power supply.
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