HP 1200W PSU Blowing

[types007]

I have been mining for a while now, and I can't seem to find the culprit here.  I have purchased over 100 of these things here over the years.  From time to time, they would blow.  Most of the time I think it is caused by insects flying into the Adapter Boards and causing a short that makes the PSU pop.  I just wanted to know if anyone exprienced might know something that I don't know.  I have rigs that ran on one year without any issues, but there are ones that just have a lot of problems.  The rigs are setup in a garage and I think the heat attracts the bugs.

I am running 240V going into PDU units which then plugs into the PSU.
I was running 6 GPU setups, but figured out 4 GPU is just more reliable and less heat density.
I am able to run 4 GPU under one of the HP 1200w PSU.
So yesterday I was replacing a blown PSU, so as soon as I replaced it, I boot it up and it popped again within 3-5 minutes.  I was like... WTF, OK so I put another one in and it popped. $80 down the drain and I stopped.  Couldn't find anything wrong with the system but then again afraid of being an idiot and keep destroying PSUs.

So I am just curious, does the Adapter Breakout Boards ever go bad that can cause this?  Or can a bad USB riser cause this?
I haven't had a GPU gone bad before.  Also I have no Motherboard or CPU.

I have some HP PSU that are still running from day 1 for over 1.5 years.  Just can't identify the point of failure.  I have seen little flying moth type of bugs fried near my rigs and seen them cause arcing before.  Wondering if it could be something else.

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[ten9]

2 of these popped with quite big bang 3-5 minutes after i plugged them in. They were DPS-1200FB A versions, bought from the ebay.
I suspect it is just faulty fan what does not start up, dust or whatever reasons since these were second hand. I checked the second one with thermal camera and the surface temp got over 100c just before it popped, in normal situation, the fan will start when the surface temp is somewhere near 60-70c already.

I do not use any adapter boards, i direct solder the wires.

[types007]

Thanks for the reply.  Ok I guess they do fail from time to time.  You won't believe how many of these PSU I have purchased for the past year. 
I did find one good thing is the fans are pretty strong for its size and can be used to cool other stuff like broken fans on GPUs.  I haven't had a fan go bad yet, but these suckers output a lot of CFM.

[gt_addict]

Do you find the more load the psu has the faster than fan gets? Only reason i ask is that im going to switch to one of these PSUs and dont want to end up burning the house down lol

[types007]

Not all of the PSU were the same.  Most of them did ramp up the fan under higher load. 
To be safe I would only run them up to 800W for 110V instead of the rated 900W @ 110V.

I did have one melt the wires at a house, each socket is only good for 1400W.  At 1600W the breaker will trip and the wires behind the drywall begin to get pretty warm and dangerous.

[NiHaoMike]

Are you making sure you're not using more than 80% of the rating?

[HagssFIN]

Are you making sure you're not using more than 80% of the rating?

Server power supplies can handle the 100% rated power. The 80% rule is only for computer ATX psus.