Fried a generic 850w PSU with 2 R9 280Xs

[uranian]

A cautionary tale about cheap/nasty PSUs; I've just watched sparks fly from my supposed 850w generic PSU when trying to run two 280Xs off it. One card was drawing around 320w, the other around 300w, the machine itself around 80w, so total power draw was in the region of 700w, i.e. 20% less than the PSU was supposed to be able to cope with.

This has got me slightly paranoid about a replacement PSU; I'm looking at the Corsair RM750, as it's gold rated and I read that Corsair are a good brand. Even without undervolting the cards, the maximum usage should be 700w, is that a reasonable ask of a decent 750w PSU?

[llamabucket]

Ouch that sucks
But, why are your 280xs drawing 300W of power? They should be around 250W each. How did you measure?

[uranian]

I've got a plug in power meter that displays how many watts the machine is using. Turns out that the two identical cards were drawing different amounts of power, the one using less power was actually getting around 20kh/s more. Better chunk of silicon, I guess. I see from the site below reports of 280Xs using anywhere from 250w to 350w.

Just hoping that the death of the PSU hasn't damaged any of the hardware. I have no way to check right now as I've got no other PSU.


https://litecoin.info/Mining_hardware_comparison/raw_data

[llamabucket]

350W for a 280x is crazy! A properly undervolted 280x should be maxing out around 250W.

What are all your components in the system and what is your watt meter reading at the wall?

[Gazza1]

You should put generic psu in the title.  Everyone knows generic psu's suck and overrate their stats

you also should undervolt your cards with VBE7. 280x's undervolt very very well.

[uranian]

GPUs: R9 280X 11221-00-20G (Sapphire AMD Radeon R9 280X 3GB Dual-X)
Mobo: ASRock B75 Pro3
HDD: Maxtor DiamondMax 21 80 GB, (STM380215AS)
CPU: Celeron G1620 2.7Ghz
RAM: 4Gb DDR3 1600Mhz

The system with no GPUs running was drawing around 80w with both GPUs plugged in and idling, 60w with just one GPU idling. One GPU was then using 320w at 100% usage, the other 300w, with no undervolting, hence total power draw was 700w. The PSU was supposed to 850w.

Anyway, what concerns me more is that this doesn't happen again. If I get a decent brand of PSU that's rated to 750w like that Corsair, will it actually be enough to power this system, or do I need to be including something that I've forgotten? I've seen some mention of power factors, I've been assuming that a 750w PSU would power 750w of equipment, but I'm starting to doubt this now.

[Gazza1]

The Corsair 750w will power the system just fine.  But I would get an 850w for headroom.

All my Corsair 850w power 3 280x without a hitch. (undervolted)

the difference between a good brand psu and any generic one is the same as comparing a Ferrari to a Yugo.

[Bobsurplus]

The Corsair 750w will power the system just fine.  But I would get an 850w for headroom.

All my Corsair 850w power 3 280x without a hitch.

I got 3 280x's and I had a 1000W psu and it still was not enough.. I had to buy an other 450w to power the third card.

I noticed the brand new cards draws more power then an older card (6+months old)

all my rigs are now powered off 2 psu's and since then have been running very smooth.

[Gazza1]

The Corsair 750w will power the system just fine.  But I would get an 850w for headroom.

All my Corsair 850w power 3 280x without a hitch.

I got 3 280x's and I had a 1000W psu and it still was not enough.. I had to buy an other 450w to power the third card.

I noticed the brand new cards draws more power then an older card (6+months old)

all my rigs are now powered off 2 psu's and since then have been running very smooth.

What PSU were you running, what brand

I have a system in the living room even powering 3 280x Toxic and a mobo/cpu and the psu isn't even putting out hot air.  Corsair HX850.

Many of the PSUs people are lead to believe are good brands, really aren't that great.

[uranian]

When I've got the GPUs undervolted, I'm hoping as llamabucket noted to be drawing closer to 250w than 300w, so the system should then be using about 580w, i.e. about 77% of the PSU's rated capacity. Why would I need the extra 100w of headroom? I don't intend to add any other GPUs/other hardware to the system. I'm intending to build a few of these, so trying to get the hardware right at this stage, and hadn't counted on the 850w PSU dying so quickly...I had figured it was worthwhile replacing it, but not within minutes, lol.

[Bobsurplus]

The Corsair 750w will power the system just fine.  But I would get an 850w for headroom.

All my Corsair 850w power 3 280x without a hitch.

I got 3 280x's and I had a 1000W psu and it still was not enough.. I had to buy an other 450w to power the third card.

I noticed the brand new cards draws more power then an older card (6+months old)

all my rigs are now powered off 2 psu's and since then have been running very smooth.

What PSU were you running, what brand

I have a system in the living room even powering 3 280x Toxic and a mobo/cpu and the psu isn't even putting out hot air.  Corsair HX850.

Many of the PSUs people think are good brands, really aren't that great.

They are enermax 1000W gold revolution 87+

they fucking suck!

[FlyForFun]

I've got a plug in power meter that displays how many watts the machine is using. Turns out that the two identical cards were drawing different amounts of power, the one using less power was actually getting around 20kh/s more. Better chunk of silicon, I guess. I see from the site below reports of 280Xs using anywhere from 250w to 350w.

Just hoping that the death of the PSU hasn't damaged any of the hardware. I have no way to check right now as I've got no other PSU.


https://litecoin.info/Mining_hardware_comparison/raw_data

You overclocked too much, your GPU won't last long...

[Gazza1]

They are enermax 1000W gold revolution 87+

they fucking suck!

I am surprised, enermax was good back in the day

[llamabucket]

All my rigs use two Corsair HX850 power supplies (total of 1700W). I've got rigs running six 7950s using two HX850s and rigs running five 280x's using two HX850s.

I honestly think that getting a fantastic power supply like the Corsair will mean a world of a difference in any rig!

[uranian]

I've got a plug in power meter that displays how many watts the machine is using. Turns out that the two identical cards were drawing different amounts of power, the one using less power was actually getting around 20kh/s more. Better chunk of silicon, I guess. I see from the site below reports of 280Xs using anywhere from 250w to 350w.

Just hoping that the death of the PSU hasn't damaged any of the hardware. I have no way to check right now as I've got no other PSU.


https://litecoin.info/Mining_hardware_comparison/raw_data

You overclocked too much, your GPU won't last long...

Lol I haven't OCed the GPUs at all. Interesting random guess, though.

[Gazza1]

All my rigs use two Corsair HX850 power supplies (total of 1700W). I've got rigs running six 7950s using two HX850s and rigs running five 280x's using two HX850s.

I honestly think that getting a fantastic power supply like the Corsair will mean a world of a difference in any rig!

Absolutely.  Corsair, Seasonic, or Antec HCP/Signature.  Silverstone is great too but their warranty is only 3 years vs the others.  XFX is also great since most of them are made by Seasonic, but I hear their customer service department isn't the best these days.

Seasonic Makes a lot of the good ones that are rebranded.

[uranian]

All my rigs use two Corsair HX850 power supplies (total of 1700W). I've got rigs running six 7950s using two HX850s and rigs running five 280x's using two HX850s.

I honestly think that getting a fantastic power supply like the Corsair will mean a world of a difference in any rig!

Yeah I spent yesterday reading around PSUs and came to the conclusion that I'd need to swap out the one I had; I just hadn't counted on it crapping out at 80% of its capacity within minutes  

Thanks for the help, I will go find a decent Corsair PSU and start again. And sincerely hope I've not fried anything with that shite PSU.

[FlyForFun]

I've got a plug in power meter that displays how many watts the machine is using. Turns out that the two identical cards were drawing different amounts of power, the one using less power was actually getting around 20kh/s more. Better chunk of silicon, I guess. I see from the site below reports of 280Xs using anywhere from 250w to 350w.

Just hoping that the death of the PSU hasn't damaged any of the hardware. I have no way to check right now as I've got no other PSU.


https://litecoin.info/Mining_hardware_comparison/raw_data

You overclocked too much, your GPU won't last long...

Lol I haven't OCed the GPUs at all. Interesting random guess, though.

That is weird, may I know which brand of GPU you are using? Gigabyte?