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I think I OCP my multi rail PSU. help needed..

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February 5, 2014 3:42:21 AM

Hello to evybody!

I currently own
XFX R9 280x card
AMD 955
AsRock 970 extreme 3
PSU is a LC6650GP3 , and I think is currently not handling the setup because I get sudden and complete shutdowns and the "Kernel power error 41" in the windows log while gaming (curiosly running 3D mark, or Passmark is fine..)
I think the cause is one of the +12V rails being over saturated and OCP kicking in, probably by the GPU.

The PSU specs are
+12V1 25A
+12V2 27A
max. combined 550W
total (with 3 and 5V) 650W

I measured the total power consumption from the outlet with a thinamajig I own and it peaks at about 330W while gaming. And that is the total from the plug so, including efficiency, the psu is outputting no more than 300W. That is way below the 550W of the 12V rails combined declared, let alone less than the 650W total.
(But even supposing ALL the power is sucked by the GPU a 27A rail should hold it!)

Cables are not colour coded for the diffrent 12V rails so I have no way of knowing which cables are which rail without tearing the thing apart. LC Power is not responding to my email (yet). Is there another way to find out?

Am I doing something wrong? Missing something?

a c 119 ) Power supply
February 5, 2014 4:06:12 AM

LC-Power has a reputation for overrating their PSUs. Chances are it can't do more than ~300W and OPP is kicking in.

Get a decent 550W+ PSU from the second link in my sig.
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a c 81 ) Power supply
February 5, 2014 4:34:18 AM

Your supply comes with one 6 pin and one 6+2 pin PCI-E connector.
These will already be allocated to the +12V rails the way the manufacturer intended.
Best case scenario is to use these two connectors.

The manufacturers site gives no indication of whether these ratings are peak or sustained, or at what temperature the rating is given.
I can't find any detailed reviews for this supply, which is not a good sign.
I would suggest replacing it.

R9 280X = 250W
AMD Phenom II X4 955 = 125W
Allow 40W for other components
Total = 415W maximum sustained load
Most of this is +12V and you want to stay under 80% of the rated power.
415 / 0.8 = 519W minimum +12V rating (44A)

A good quality 550W supply would be OK, but I would choose a good supply over 600W to be safe.

Some suggestions:
XFX Pro 650
Antec HCG 620
Seasonic S12G 650
Seasonic G 650
Seasonic M12II 650
Seasonic X 650
Corsair HX 650

The XFX and Antec in the list are manufactured by Seasonic, but sold at a good value price under other brands.
The Seasonic S12G and G are both 80 plus gold rated, each is available in different markets.
The Seasonic X series is 80 plus gold rated with some extra features at a higher price.
The Corsair HX is a great supply, but usually more expensive the equivalent Seasonic units.
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February 5, 2014 5:35:35 AM

Thx for the replies guys

so no "smart" rail management is possible her, am I right?

checked your PSU reccomendations in my country (Italy) and I would go with the XFX 650W I find for what I think is a good price (70€).
BUT the XFX website suggests as a MINIMUM req for my R9 280x the Pro750W (single rail 62A), and suggested the 850W. Isn't that complete overkill? they are just trying to sell the pricier ones?
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a c 81 ) Power supply
February 5, 2014 5:48:54 AM

the_only_pinoz said:
Thx for the replies guys

so no "smart" rail management is possible her, am I right?

checked your PSU reccomendations in my country (Italy) and I would go with the XFX 650W I find for what I think is a good price (70€).
BUT the XFX website suggests as a MINIMUM req for my R9 280x the Pro750W (single rail 62A), and suggested the 850W. Isn't that complete overkill? they are just trying to sell the pricier ones?


As you have found with your current PSU, plenty of power supplies carry very optimistic ratings.
The card manufacturers, as well as Nvidia and AMD try to be conservative enough for worst case scenario of cheap PSU and other power hungry components.
The XFX Pro 650 will be a great choice.
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a c 119 ) Power supply
February 5, 2014 5:56:31 AM

If by 'smart' you mean shifting stuff between rails, then no, probably not. I doubt it's even a multi-rail PSU; that adds extra cost.

That's complete overkill. I'd be fine with TWO 280Xs on an 850W.

I'd be perfectly happy with the 550W if you weren't OCing much.
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February 5, 2014 9:16:58 AM

thanks so much guys. I'll go with the XFX Pro 650W because 550W is not available this way I have some head room in case I wanna mess with stuff in the future

too bad for the LC Power, it honestly looks well built and polished, cables look resistant enough, 90mm fan in very silent, it ran apparently always cool (bottom mounted in what I think is a GREAT bang for buck case, the Thermaltake element T), many protections (OCP, OVP, UVP, SCP, OTP, OPP), 80PLUS bronze... and it was cheap at 55€
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a c 81 ) Power supply
February 5, 2014 1:37:50 PM

the_only_pinoz said:
thanks so much guys. I'll go with the XFX Pro 650W because 550W is not available this way I have some head room in case I wanna mess with stuff in the future

too bad for the LC Power, it honestly looks well built and polished, cables look resistant enough, 90mm fan in very silent, it ran apparently always cool (bottom mounted in what I think is a GREAT bang for buck case, the Thermaltake element T), many protections (OCP, OVP, UVP, SCP, OTP, OPP), 80PLUS bronze... and it was cheap at 55€


I'm sure it is a better supply than many provided with cheap cases.
For someone with a 100W graphics card it is probably fine.
Your 250W card is just too much for it.
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February 6, 2014 12:51:52 AM

well wow, specced at 550W, so 45A, and tested at 33A. So maybe those specs are peak values, not sustained
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a c 119 ) Power supply
February 6, 2014 1:13:59 AM

No, Ecova pulled 593W out of it.

Remember that there's also 3.3/5V, plus the -12V and 5VSB.
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February 6, 2014 1:29:16 AM

Someone Somewhere said:
No, Ecova pulled 593W out of it.

Remember that there's also 3.3/5V, plus the -12V and 5VSB.


sure but the specs on the PSU itself state a total 550W for the 12V rails combined only. 650W in total including 3.3/5
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a c 119 ) Power supply
February 6, 2014 3:00:52 AM

Ecova's report doesn't have the full specs. You can read the PDF, but they say the rated output power is 600W.

Their full load test was 32.8A@12V, 0.7A@-12V, 23.3A@3.3V, 20.5A@5V, and 2.6A@5VSB.

Lots more load on the minor rails; indicative of an outdated design.
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February 6, 2014 5:25:11 AM

Yeah I've read the pdf, thank for the link btw.

Just to share my story: I got a reply from LC Power support (and I've linked this thread to them). Here's the conversation

Me: Hi, I would like to know how are the two 12V rails divided into (which cables are from which rail).
LC: he two 12V rails are the two yellow ones on the 20+4 pin connector
Me: how is that possible? what about the CPU 4+4, isn't that 12V? and the the GPU's 6 and 6+2 also 12V?
LC: sorry...12V1 is for the mainboard and 12V2 for PCI.

...
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a c 119 ) Power supply
February 6, 2014 5:51:46 AM

The ATX standard originally called for the CPU to be on 12V2, and everything else to be on 12V1. However, with the increased power consumption of GPUs over the last decade or two, that's caused some trouble.

Most modern PSUs use either one rail or four (usually PCIe 1, PCIe 2, CPU, and everything else).

Personally, I'd toss it and pick up something decent.
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February 6, 2014 5:54:08 AM

and toss it I will..

thx again for the help to all of you

p.s. 650W PSU for sale, anyone interested? ;) 

Someone Somewhere said:
The ATX standard originally called for the CPU to be on 12V2, and everything else to be on 12V1. However, with the increased power consumption of GPUs over the last decade or two, that's caused some trouble.

Most modern PSUs use either one rail or four (usually PCIe 1, PCIe 2, CPU, and everything else).

Personally, I'd toss it and pick up something decent.


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February 7, 2014 1:20:40 AM

so LC Power answered once again, this time sending me a pdf with the complete description of the cable layout (in german btw..).
It appears that the ONLY thing in the 2nd 12V rail is the GPU connectors (a 6+2 and a 6 both splitting up from the same cable). Which is rated mx 27A on the official specs
just wanted to let you know
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February 8, 2014 11:04:29 AM

sorry for switching accounts.. still OP here. and sorry if I insist keeping this thread alive but I just cannot wrap my head around this...

If it IS the PSU not handling the R9 280x then why am I not able to reproduce the shutdown with stress tests and such?
I managed to pull of 350W from the outlet with Passmark and AMD overdrive running simultaniously but still no shutdown. It just happens whith darksiders 2 I realized and with less than 350W. But searching on other fora gave no solution (and shows this can happen with other games aswell so I am determined to understand the cause or find a solution). I tried audio drivers, USB3 drivers, HDD tests, forcing v-sync.. nothing

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