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PSU Questions

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September 15, 2012 9:39:09 AM

I'm going to build a new pc and I was thinking of buying the OCZ 550W FATAL1TY SERIES PSU so I would like to know what your opinion is, regarding:
1. The amperage (My graphics card would be an AMD 7870. Can the PSU handle it?)
2. The two 12V rails (Is this a problem? Is a single 12V rail better?)
3. What about the CORSAIR CMPSU-600CXV2 BUILDER SERIES 600W? It's not so gaming-like but is it better? Please not that the OCZ is modular with 2 12V rails while the Corsair is non-modular with a single 12V rail.
4. Is there any other PSU with 80+ BRONZE Certificate at the same wattage, amperage and price? If not then there is no problem, right?

If possible don't recommend me any more expensive PSUs. Just so you know, I'm not planning to OC or Crossfire.

My System Components:
THERMALTAKE V4 BLACK EDITION

Asrock H77 Pro-4/MVP

Intel Core i5-3450 or 3470 or 3550 or 3570

Corsair XMS3 8GB DDR3 Non ECC CL9 1600MHz

AMD Radeon HD7870 GHz Edition 2GB DDR5 PCI-E DVI HDMI Dual Mini-DP (Sapphire)

Seagate Barracuda 1TB SATA3 HDD

COOLERMASTER R4-L2R-20AC-GP LONG LIFE LED FAN 120MM

More about : psu questions

a c 243 ) Power supply
September 15, 2012 11:48:37 AM

1. Yes
2. No, and only if the multi rail is poorly designed
3. If modular isn't a big concern I'd take it over an OCZ
4. No idea what kind of pricing you're looking at
September 15, 2012 12:52:04 PM

delluser1 said:
1. Yes
2. No, and only if the multi rail is poorly designed
3. If modular isn't a big concern I'd take it over an OCZ
4. No idea what kind of pricing you're looking at


Thank you for replying!
The price I'm looking for is around 70€.
What is your opinion about the Coolermaster GX-550w? It's more gaming-like than the corsair builder 600w with a maximum output capacity of 660w, 44a on the 12V rail and an 80+ BRONZE certificate (85% typical). (The OCZ and the Corsair I mentioned don't have bronze). It costs 75€ which is nice!
After browsing TH I read a recent article which stated that AMD is going to cut the prices of some GPUs including the price of 7950 at 300$ which is about 240€ (exactly how much the 7870 would cost now). If this happens next week as stated in the article, I'll go with the 7950.

http://www.coolermaster.com/product.php?product_id=6641
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a c 243 ) Power supply
September 15, 2012 1:00:01 PM

DimShadowen7 said:
Thank you for replying!
The price I'm looking for is around 70€.
What is your opinion about the Coolermaster GX-550w? It's more gaming-like than the corsair builder 600w with a maximum output capacity of 660w, 44a on the 12V rail and an 80+ BRONZE certificate (85% typical). (The OCZ and the Corsair I mentioned don't have bronze). It costs 75€ which is nice!
After browsing TH I read a recent article which stated that AMD is going to cut the prices of some GPUs including the price of 7950 at 300$ which is about 240€ (exactly how much the 7870 would cost now). If this happens next week as stated in the article, I'll go with the 7950.

http://www.coolermaster.com/product.php?product_id=6641

Same as most everyone else, don't do it, output quality is pretty poor
Very little ( read insignificant ) difference between 80+ and 80+ Bronze, wouldn't let it sway me
September 15, 2012 1:15:49 PM

delluser1 said:
Same as most everyone else, don't do it, output quality is pretty poor
Very little ( read insignificant ) difference between 80+ and 80+ Bronze, wouldn't let it sway me


Ok I'll go with the Corsair or the OCZ PSU. Just one more question:
The OCZ has 2x 25A 12V rails. Does that mean that its total amperage on the 12V rail is 50A? If not please explain why.
a c 243 ) Power supply
September 15, 2012 1:43:44 PM

The rails are not additive
Combined output is 450 watts ( 37.5a )
a c 137 ) Power supply
September 15, 2012 2:01:29 PM

DimShadowen7 said:
Ok I'll go with the Corsair or the OCZ PSU. Just one more question:
The OCZ has 2x 25A 12V rails. Does that mean that its total amperage on the 12V rail is 50A? If not please explain why.


1. The 7870 needs a 500w psu and two 6 pin pci-e power connectors. The OCZ550w qualifies.

2. Not an issue. UL reconnends an upper limit to the amperage delivered to independent rails for safety reasons. But, in fact, most power supplies actually have only one power generating rail. Two or more rails are usually just an artificial division.

3. I don't think any psu has a "gaming like" characteristic. Corsair is a good brand, and the 600w builder series unit would be OK.
You may be confused about the term "modular". It does not refer to the number of rails, but to the ability to detach unused leads from the psu. It is nice perhaps from a cable management point of view, but it has no bearing on performance. With a properly sized psu, you will be using most of the leads anyway.

4. I have no idea on european prices.

5. The +12v amps is the real metric for the power a psu can deliver. That is what a graphics card needs, and is the most power hungry component of a gaming rig. You can't just add the amps for each rail. The amps is the maximum that the rail can deliver, but remember that there is usually only one source of power that generates the amperage. In a top quality psu, like th Seasonic 520w unit
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
The sum of the two rails does actually equal 40a.
The way to tell is to look at the data plate which will give you the total amps for all the 12v rails. Sometimes it is expressed in watts, and you then divide by 12.
Here is the data plate for the Seasonic 520 psu:
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
Now, contrast that with the data plate from the 550w OCZ unit:
http://www.ocztechnology.com/ocz-550w-fatal1ty-series-p...
You will see that the maximum power os only 455w, or 37.9a.

6. I would not worry about bronze/silver ratings etc. The you will never make up the difference in electricity savings. I would buy a silver or gold rated psu if you need a quiet psu. Because they are more efficient, the fan will not spin up so quickly to provide cooling.

7. The simple thing to do is to always buy a quality brand psu. You are safe with Seasonic, Corsair, Antec, XFX, and PC P&C to name a few. OCZ is iffy. A quality psu will deliver the power it advertises. It will do so continuously, with more available at peak.
And, it will deliver that power at case temperatures, near 50c.
A cheap unit will advertise peak power, at room temperature, and not on the +12v rails where you need it.
A cheap psu is the last place to economize on a pc. If it fails, it can destroy anything it is connected to.
Bottom line, buy only a quality psu. Here is one list of psu quality tiers:
http://www.eggxpert.com/forums/thread/323050.aspx
September 16, 2012 11:51:19 AM

Ok thank you guys!
!