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PSU for two GTX 460?

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October 21, 2010 10:45:16 AM

My friend is gonna get new pc and will have a processor i5 650,1600mhz 4GB ram and i think asus P7P55D-E PRO mobo also she will have two nvidia GTX 460 1GB in SLI mode.

Wich psu is the best under 65$

we picked this one for now:

http://www.newegg.com/Product/Product.aspx?Item=N82E168... - RAIDMAX HYBRID 2 RX-730SS - it has two +12@24A

I search for a bit and find few others:

http://www.newegg.com/Product/Product.aspx?Item=N82E168... - Rosewill Green Series RG630-S12 630W - it has a single +12@50A

http://www.newegg.com/Product/Product.aspx?Item=N82E168... - Rosewill RV2-700 700W - it has two +12@28A

Are these psu good, wich the best for that money? What whould be your pick if you had this system? and please can you suggest me one under 65$ :) 

More about : psu gtx 460

October 21, 2010 12:33:57 PM

that only has four 18Amps?
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a c 277 ) Power supply
October 21, 2010 1:45:07 PM

The per rail current available isnt nearly as important as the total current available. The Raidmax you picked has at most, 48A available between its 12V rails, the Seasonic has 52A available for its rails to share so while it looks to be lower, its actually a fair bit more powerful since i doubt the rails on the raidmax can actually be added, it likely only has ~45A available.
October 21, 2010 1:51:50 PM

4x18 = 72AMPS overall.
Seasonic seems to be an excellent PSU, stable wattage and genuine wattage!

Some PSU manufacturers over hype there wattage on there PSU's, meaning they actually cant pump out there labeled wattage, i believe Seasonic to be one of the few that can.
a c 243 ) Power supply
October 21, 2010 1:53:51 PM

reccy said:
4x18 = 72AMPS overall.

:pfff: 
72 amps = 864 watts, not going to happen, even with a Seasonic
October 21, 2010 1:57:18 PM

delluser1 said:
:pfff: 
72 amps = 864 watts, not going to happen, even with a Seasonic


I was told thats how it works, obviously im wrong. So care to explain on how it works out, rather then being egotistical by just commenting on my error?
a c 243 ) Power supply
October 21, 2010 2:31:55 PM

reccy said:
I was told thats how it works, obviously im wrong. So care to explain on how it works out, rather then being egotistical by just commenting on my error?

Not being egotistical, thought it was something you would know, you did make the reccomendation.
The label on the Seasonic clearly states what the combined 12v output is, and hunter did mention it in his post.
October 21, 2010 2:38:04 PM

delluser1 said:
Not being egotistical, thought it was something you would know, you did make the reccomendation.
The label on the Seasonic clearly states what the combined 12v output is, and hunter did mention it in his post.


That PSu is stated as being "SLI" ready, this surely means it can cope in a "SLI" scenario? Or care to elaborte on this?

It has 52A on its 12v rails.. I missed that, i didnt examine the label in detail..

Seasonic seems a good brand, so care to recommend something better, or you just gonna be negitive ;) 
a c 243 ) Power supply
October 21, 2010 2:42:15 PM

reccy said:
That PSu is stated as being "SLI" ready.

Seasonic seems a good brand, so care to recommend something better, or you just gonna be negitive ;) 

Don't know what your problem is.
There's a little thumbs up or down on these posts for rating purposes, I'm the guy who gave you the thumbs up.
You gave a very good reccomendation, you're a regular who has been here for quite some time, I simply expected that you would know how to determine the 12v output.
October 21, 2010 3:14:09 PM

delluser1 said:
Don't know what your problem is.
There's a little thumbs up or down on these posts for rating purposes, I'm the guy who gave you the thumbs up.
You gave a very good reccomendation, you're a regular who has been here for quite some time, I simply expected that you would know how to determine the 12v output.


And i thought i did, i didnt question the "expert" who told me, as i thought he was the expert in this scenario. ive always been told that you add up the values on the 12v rails. Hense why i suggested 4x18 = 72a

650watts / 12volts? = 54.11111amps?? thats the cloest i can get to the stated 52A actually labelled.

Im not sure if the above it he way you would work out the amps, i have been stood corrected that its not the way above. Can only apologise on this.
October 21, 2010 4:49:31 PM

ok im bit confuzed here hunter said it has 52A? on the site it say 18A

Whouldnt i be limited to 18A? i dunno i readed somewhere that x4 is just splited and still feeds from same source so system takes i dunno lets say 5 amps and gpus x2 10 amps whouldnt that be 15 amps for entire system? or something like that wich whould be close to 18A? i dunno im just being random x.x
a b ) Power supply
October 21, 2010 7:01:28 PM

its has 52 amps available on the 12 side of the psu but its split up into 4 rails that can handle maximun load of 18a per rail but not on all the rails the same time but all the rails together can handle 52a
October 21, 2010 9:08:53 PM

just on a side note if she ever upgrades lets say to I7 and some more demanding sli grapgic card whould it be enogh?
a b ) Power supply
October 21, 2010 9:21:04 PM

650 should be enough for up to 2x5850/6850/6870/sli460/sli450
a b ) Power supply
October 21, 2010 9:28:57 PM

reccy said:
And i thought i did, i didnt question the "expert" who told me, as i thought he was the expert in this scenario. ive always been told that you add up the values on the 12v rails. Hense why i suggested 4x18 = 72a

650watts / 12volts? = 54.11111amps?? thats the cloest i can get to the stated 52A actually labelled.

Im not sure if the above it he way you would work out the amps, i have been stood corrected that its not the way above. Can only apologise on this.

It's watts divided by volts to get the amperage.
a c 277 ) Power supply
October 21, 2010 10:30:28 PM

Alright, since there seems to be a bit of confusion here, here is a nice summary of how the rails on a PSU work. There is a main 12V source in most modern PSUs, the rails all branch off of this one source, each rail in this case will let you pull 18A off of it, but this doesnt mean you can draw 18A from all four rails at the same time, in fact rarely can you load up all the rails to their max level since the 5V and 3.3V rails are usually created off of the 12V rail as well. The 18A per rail limit is about where the over current protection limit is, this helps prevent damage in the event of a short circuit, but in the end all the rails are drawing from the same source, in this case a source that can only provide 52A spread between its rails.
October 22, 2010 4:37:37 AM

I'd recommend a different CPU, your friend would be better off with an i5 750 or higher. The 650 is only dual core and if your friend has the money to buy 2 460's then why not spend $30 more on a quad core CPU? That CPU + that motherboard should have no problem comfortably over clocking it well beyond the 650's clock rate so that would make for a much more balanced system with those 2 power houses for graphic cards in there.

As for the power supply issue, I don't mean to sidetrack the thread but don't you need a rail per graphic card, so 2 for this setup? I haven't setup an SLI pc yet but I was under the impression you'd need a power supply with 2 12v rails, yet I'm noticing some SLI certified power supplies on newegg that only list a single 12v rail so that's getting me confused.
October 22, 2010 8:19:10 AM

2 rails are just splited and are still powering from the same source. There shouldnt be a difference betwen sinlge and multiple rails? and as long as you got enogh pcie connectors for SLI, whatever thats single or multiple rails you will able to power it... i think?

So if she goes with i5 750 + two GTX 460 in SLI mode + 4Gb 1600mhz + P7P55D-E PRO + 3 fans + aftermarket cooler and maybe later on a TV tuner card.

Will the Seasonic you guys picked enogh for the system?
a c 277 ) Power supply
October 22, 2010 8:02:53 PM

The number of rails in a PSU is not relevant, and you certainly dont need one rail per GPU, there are many PSUs with large single rails that work just fine, and there are others with multiple smaller rails that work just fine, there really isnt a benefit to single or multirail for the consumer. Read the JonnyGuru FAQ on it
http://www.jonnyguru.com/forums/showthread.php?t=3990

The 650W seasonic will be fine for that system.
October 24, 2010 3:19:54 AM

Corsair tx650w
!