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Whats enough amps on the +12V rail?

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August 11, 2011 7:59:01 AM

ok iam shopping for a psu for my 1st build which will be used mainly for gaming and browsing the net. so far its the following:
i3-2100, 4gb ddr3, asrock h61 board and one of the following:
gts450, gtx460, 6770 depending on price as iam on budget and will be gaming on 720p 19" lcd.
wont be overclocking/SLI/Crossfire

how do i find out the +12v rail amps on a particular psu as most vendors dont mention it?

extreme psu calculator says i need about 400w for this build i will probably go 500w to be safe and if i might upgrade

so apart from wattage, +12v rail amps, warranty, noise. number of sata/4pin cables and brand,
is there anything else i need to watch out for?

also the case iam getting (xigmatek white knight) has the psu at the bottom, is this ok? or is it better at the top?

More about : whats amps 12v rail

a b ) Power supply
August 11, 2011 8:57:00 AM

gogoman123 said:
ok iam shopping for a psu for my 1st build which will be used mainly for gaming and browsing the net. so far its the following:
i3-2100, 4gb ddr3, asrock h61 board and one of the following:
gts450, gtx460, 6770 depending on price as iam on budget and will be gaming on 720p 19" lcd.
wont be overclocking/SLI/Crossfire

so for those cards whats enough amps on the +12V rail? and how do i find out as most websites dont mention it?

extreme psu calculator says i need about 400w for this build i will probably go 500w to be safe and if i might upgrade

so apart from wattage, +12v rail amps, warranty, noise. no of sata/4pin cables and brand,
is there anything else i need to watch out for?

also the case iam getting (xigmatek white knight) has the psu at the bottom, is this ok? or is it better at the top?


PSU for PC main power use +12V , +5v and 3.3V, 400W - 500W not enough for OC / SLI you need more power when use SLI or Crossfire , you'd better double check what system are you going with a VGA plug, not the speed that will get rather bottleneck wiill you get
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a c 243 ) Power supply
August 11, 2011 10:22:48 AM

gogoman123 said:
thanks alot funsurfer, that guide is great. but how can i find out the +12v rail amps on a particular psu as most vendors dont mention it?
how do i find out the +12v rail amps on a particular psu as most vendors dont mention it?
so for example, is the +12v amps on this one 25A? or is this combined with somethind else? http://www.ocztechnology.com/ocz-550w-fatal1ty-series-p...

On many it's guess work, the label on the OCZ gives you the info
2 x 25a rails with 450 watts available
450w / 12v = 37.5a combined output

If that kind of info is not available on the psu label it's not worth buying IMO
a c 83 ) Power supply
a b 4 Gaming
August 11, 2011 10:31:32 AM

Look up the PSU on newegg. They nearly always have a pic of the chart on the side of the PSU. If its a single rail unit the amps will be listed, 30A or whatever. If its a multi rail unit, look for the statement that says "12v1 + 12v2 + 12vN not to exceed xxxW." Divide this number by 12 to get the amps. For example, 408W / 12V = 34A.

I agree with Dell. If you can't find this info, just move along. There is a good reason why they don't list it, and you won't want it for the same reason.
August 11, 2011 10:46:35 AM

gogoman123 said:
thanks alot funsurfer, that guide is great. but how can i find out the +12v rail amps on a particular psu as most vendors dont mention it?

so for example, is the +12v amps on this one 25A? or is this combined with something else? http://www.ocztechnology.com/ocz-550w-fatal1ty-series-p...


+1 to delluser1
August 11, 2011 10:47:24 AM

ok so if i divide the max +12V rail wattage by 12 i get the combined amp output
if this is for the gpu, what other components is this combined with? so that i can subtract their amps and check if theres enough amps left for the gpu, or is this wrong?

also, should i get single or mulkti +12V rail unit?
August 11, 2011 11:08:51 AM

gogoman123 said:
ok so if i divide the max +12V rail wattage by 12 i get the combined amp output
if this is for the gpu, what other components is this combined with? so that i can subtract their amps and check if theres enough amps left for the gpu, or is this wrong?

also, should i get single or mulkti +12V rail unit?


The 12V rails don't supply power just to the graphic card but also to the CPU, HDD, DVD-ROM and all the other components that the yellow and black wires from the PSU reach to. From all those other components the CPU is the most demanding and all of them are taken into consideration when the vendor publishes the PSU's data.

The graphic card is usually the most power hungry part in the PC so you just have to look for its power consumption and buy a good brand PSU according to that.

Single 12V rail is better (like in Corsair PSUs)
August 11, 2011 11:14:43 AM

ok thanks. so i should get a psu that provides more 12v rail amps than the gpu requirement as it will be powering the cpu as well as other components, right?

also if it says on it that it supports SLI/Crossfire, is it safe to assume that it provides enough 12v rail amps if this info is not mentioned?

what do u think of this one: http://www.ebuyer.com/234911-thermaltake-575w-toughpowe...
August 11, 2011 11:42:01 AM

gogoman123 said:
ok thanks. so i should get a psu that provides more 12v rail amps than the gpu requirement as it will be powering the cpu as well as other components, right?


I meant in the former reply that the 12V power requirement of a GPU includes all the components and not just the GPU so you don't have to buy a PSU that provides more 12v rail amps than the GPU requirement but it is highly recommended that you will get one with more amps (5 or 10) because PSU's power output diminishes over time.
August 12, 2011 1:55:40 PM

FunSurfer said:
what do u think of this one: http://www.ebuyer.com/234911-thermaltake-575w-toughpowe...


yeah thnks, i came across it too and thought it was good. so u think 575w and it has good enough cooling? also it says that "Max Operating Temperature 50 °C" is this not good enough? thanks 4 ur help
a b ) Power supply
August 14, 2011 7:56:36 PM

Out of all those , The thermaltake is the better one with the CX 600 V2 coming in close. Don't even think about the coolermaster. GX Serries are crap.


Using SLI or crossfire for both of these is not recommended since under load, it'll be pushing nearly 80% of the PSU capacity. For SLI or Crossfire, go for 750w+ units preferably.

August 14, 2011 8:11:28 PM

thanks lilotimz. no i wont sli/crossfire or overclock anything.
a b ) Power supply
August 14, 2011 10:24:32 PM

Then get the Thermaltake or CX 600V2

Both are good quality PSU's with the thermaltake one being a tad better.

Good luck :) 
!