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Two PSUS? Is one enough?

Last response: in Components
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May 26, 2012 7:10:26 PM

Hey,

I have a good system, running an i5-2500k, asus p8z68-v lx, a 7200RPM SATA Hard drive (black), a Cd/DVD burner, 2 fans and finnaly a cooler master eXtreme PowerPlus 600watt PSU.

The PSU only has 600 watts, and to be more specific, two 18A 12volt rails.

I returned my 6770, and am looking to buy an overclocked Radeon 6870 900m edition
http://www.tigerdirect.ca/applications/searchtools/item...

I have a 400 watt Dell PSU from my old computer, I was considering using it to power the psu alone. Is that safe?

Is it even necessary? Can my PSU power all of that?

Finally, if its enough, how can i split up the rails?

Thanks

More about : psus

a b ) Power supply
May 26, 2012 7:20:22 PM

Yeah 600W is enough for a single 6870. That PSU isn't the best though.
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a c 158 ) Power supply
May 26, 2012 7:38:13 PM

That PSU, like most of the Extreme Power PSUs, is absolutely craptastic. At loads above 450W, there is real/significant risk of it failing and taking computer components with it. http://www.hardwaresecrets.com/article/Cooler-Master-eX...
That being said, your system load probably won't exceed 300W at full load even with an OC on CPU/GPU. http://www.guru3d.com/article/radeon-hd-6850-6870-revie...
You should be ok, but I would personally replace that PSU.
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May 26, 2012 8:32:33 PM

Rugger said:
That PSU, like most of the Extreme Power PSUs, is absolutely craptastic. At loads above 450W, there is real/significant risk of it failing and taking computer components with it. http://www.hardwaresecrets.com/article/Cooler-Master-eX...
That being said, your system load probably won't exceed 300W at full load even with an OC on CPU/GPU. http://www.guru3d.com/article/radeon-hd-6850-6870-revie...
You should be ok, but I would personally replace that PSU.



That link isn't actually true.

If you look carefully, and compare there test to the labelled specs, hardware secrets is overloading the 12v rail. When they have under 18A on each rail (the labelled amperage) the PSu performs fine. Once they exceed the labelled wattage, the PSU overloads (obviously).

So the Hardware secrets article is only proving that this PSU cannot exceed the labelled wattages.

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a c 158 ) Power supply
May 26, 2012 9:21:46 PM

Then it's more accurate to say that this is a 600W PSU that can only deliver 432W on the 12V rail....the rail that carries 80% of the load in PCs.
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Anonymous
a b ) Power supply
May 26, 2012 9:53:10 PM

mastrom101 said:
That link isn't actually true.

If you look carefully, and compare there test to the labelled specs, hardware secrets is overloading the 12v rail. When they have under 18A on each rail (the labelled amperage) the PSu performs fine. Once they exceed the labelled wattage, the PSU overloads (obviously).

So the Hardware secrets article is only proving that this PSU cannot exceed the labelled wattages.

look honestly that is an UNDER PERFORMING psu. the 12 volt rails are under powered in balance with the rest of the rails (3.3 and 5 volt).

i should know i have a XP+ 700 in my rig right now and i won't trust it above 550 watts . . .
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a c 243 ) Power supply
May 26, 2012 11:00:36 PM

mastrom101 said:
That link isn't actually true.

If you look carefully, and compare there test to the labelled specs, hardware secrets is overloading the 12v rail. When they have under 18A on each rail (the labelled amperage) the PSu performs fine. Once they exceed the labelled wattage, the PSU overloads (obviously).

So the Hardware secrets article is only proving that this PSU cannot exceed the labelled wattages.


If you read and are able to understand the review you should have noticed;
Pg 5: 43 amps is theoretically possible
Pg 6: there is no OCP, this means no limit to the output other than what the internal components are capable of providing, go back to pg 5
18 amps per rail is just another lie on the label
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May 27, 2012 6:11:09 AM

delluser1 said:
If you read and are able to understand the review you should have noticed;
Pg 5: 43 amps is theoretically possible
Pg 6: there is no OCP, this means no limit to the output other than what the internal components are capable of providing, go back to pg 5
18 amps per rail is just another lie on the label



The power supply can only deliver 18X2X12 on the 12 vrails. The test showed that the psu can deliver that, however it cannot exceed it. So to say the 12v rail is small for a 600 watt is true, but cooler master is not false advertising. The psu can deliver 600 watts, just not on the 12v alone


Is the 12v big enough for the 6970 900m OC card? thats my concern
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Anonymous
a b ) Power supply
May 27, 2012 8:02:47 AM

you will be able to use the 6970 but please understand:
that is a horrible PSU! to fail @ 18.5 amps (one half of an amp of the rated spec) on the 12 volt rail you will be plugging that card into (12vb) is not desirable. c'mon! you talking just 6 watts!

Measured power consumption - 6870
Subjective measured GPU power consumption = ~ 141 Watts

and since 18*12=216 you will have 50 watts of "room" not counting your peripherals such as hard drives. though with two 6 pin connections that provide 75 watts each and 75 watts supplied by the pci-e slot, theoretically it can suck 225 watts; which is 9 more than a single rail can handle and we know it fails @ 6 watts over . . . my point? push that card and you CAN fail.

btw, DO NOT assume those two 6 pin pci connectors are on separate rails. the first one (12va) can very easily be wired to the 12 volt in the 24 pin mortherboard connection only . . .
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a b ) Power supply
May 27, 2012 9:44:39 AM

That PSU sucks, I don't understand why you're defending it.
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May 27, 2012 9:52:48 AM

When someone comes to the forums and asks for advice and then says hes gonna do it his way anyhow, let him. If it destroys his PC he'll have learned a valuable lesson.
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a b ) Power supply
May 27, 2012 11:08:21 AM

Anonymous said:
you will be able to use the 6970 but please understand:
that is a horrible PSU! to fail @ 18.5 amps (one half of an amp of the rated spec) on the 12 volt rail you will be plugging that card into (12vb) is not desirable. c'mon! you talking just 6 watts!


On top of this great point you have to consider when dealing with a company that lies and makes terrible products with poor quality, just because hardware secrets got 18.5A on one unit doesn't mean that's the average. or that YOU WILL GET THAT FROM YOURS.

You can gamble your entire system if you want. or spend 50 or 60 bucks on a decent PSU. When everyone tells you the same thing you should listen. Its not an insult to you. MOST people don't know better when they start building. I personally have got a dead rosewill from before their quality went up and a raidmax(face palm) running a router box when it couldnt provide its rated for my rig.

Heck my first PSU in 2003 was a $20 "500W". shudder. never failed but geez. you can ignore the pro reviews and good advice but its gonna bite you.
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May 27, 2012 2:56:28 PM

unksol said:
On top of this great point you have to consider when dealing with a company that lies and makes terrible products with poor quality, just because hardware secrets got 18.5A on one unit doesn't mean that's the average. or that YOU WILL GET THAT FROM YOURS.

You can gamble your entire system if you want. or spend 50 or 60 bucks on a decent PSU. When everyone tells you the same thing you should listen. Its not an insult to you. MOST people don't know better when they start building. I personally have got a dead rosewill from before their quality went up and a raidmax(face palm) running a router box when it couldnt provide its rated for my rig.

Heck my first PSU in 2003 was a $20 "500W". shudder. never failed but geez. you can ignore the pro reviews and good advice but its gonna bite you.



I get what your saying 110%. I eventually will upgrade my PSU, but right now thats out of the picture. I will probably upgrade it in two years when the warranty ends. If i had the money, i would get a new one now, but i dont.

My PSU was able to power my 6770 perfectly. I returned the 6770, and i need a bit more GPU power. Thats why i looked at the 6870 900m OC edition.

Thats my main concern, whether it can power that card and still have a tad of power left, or if i have to default to a 7770. CM said i can easilly power the 6870, but i wanted a second opinion.

I get it that my PSU isn't the best quality, I'm not denying that. Im also not ignoring people. But wether my PSU is good is irrelevant, because i know its inferior. The concern is wether 2 12v 18a is enough to power this system.


Thanks for all you advice sofar
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a c 158 ) Power supply
May 27, 2012 3:11:41 PM

As I stated above, your Coolermaster Extreme Power Plus 600W is sufficient for your planned upgrade from a 6770 to a 6870.
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a c 243 ) Power supply
May 27, 2012 3:32:08 PM

mastrom101 said:
The power supply can only deliver 18X2X12 on the 12 vrails. The test showed that the psu can deliver that, however it cannot exceed it. So to say the 12v rail is small for a 600 watt is true, but cooler master is not false advertising. The psu can deliver 600 watts, just not on the 12v alone


Is the 12v big enough for the 6970 900m OC card? thats my concern


Like I said, you have to be able to understand what you are reading

The label claims 2x18a and doesn't give a combined max, normally these wouldn't be additive, it's very seldom that a psu can output the combined rating of the rails
We know from the review that the components are capable of producing 43a of 12v power
We also know from the review that there is no OCP monitoring
If there was the psu would have shut itself down when either of the virtual 12v rails was taken beyond it's labeled 18a rating
It didn't, in good quality power supplies that's generally considered a good thing
It did deliver 41 amps combined from both of the virtual rails, just not in spec, and burned when they tried for the 43a that the components are capable of

No-one claimed it could deliver all of it's power on the 12v, 43a is only 514w

It's a lousy power supply, but it's capable of powering a 6870 ( power for the card will be drawn from both rails ), if you choose to use it, it's your choice
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May 27, 2012 5:52:00 PM

Ok thanks everyone for your help. I think I've made my descision.

Im going to contact Cooler Master, and ask them if i can upgrade the PSU to a GX or Silent Pro series. Im going to push hard for it, and il top up the diffrence.

Next, il try to return it to Tigerdirect. The problem is i bought it about 50 days ago, and i sent in the barcode for a rebate :( 

Lastly, Il just suck it up and buy a good PSU. I've decided it's not worth the problems, especially for a computer that has to last over 5 years. Il bite the bullet myself with some of my Grad Money. My parents will probably be mad, but whatever.

I think its better to be safe than sorry. This does mean i will be broke by the end (as im buying thermal paste, the 6870, a monitor and now a power supply)

I can still use the old power supply for another purpose. I could probably give it to my Grandpa when i build hic computer, because he probably wont use more than 300 watts, and the PSU will be more then adequate for that purpose (unless you think its too inferior for even an extremly light 300 watt computer)

As for the PSU, is this a good one?

http://www.tigerdirect.ca/applications/SearchTools/item...

It looks like a good price, but i want you opinions.

Thanks so MUCH!



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a c 158 ) Power supply
May 27, 2012 7:48:09 PM

The OCZ ModXstream is a decent power supply; great value for the money.
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