# What rail does a CPU run on. PSU's



## Melvis (Sep 2, 2008)

hi all, i have a quick question about PSU's. im goin to be building a machine for a m8 real soon, but i gotta make sure the PSU is up to the task. The PSU ill be usin is a 460W coolermaster (comes with the case) and it has two 12v, 18Amp rails, max out put of 312W, and im running in it a overclocked version 8800GT from leadteck, and i was thinking, hmm thats getting a bit close in watts? but what i really wanted to know was what rail, volts etc does the CPU run on?
Is it the 5v rail? or 3.3volt rail? i think it is, but i wanted to check....

Any info would be great thanks, and its a budget build so yea cant go omg on PSU or anything.

Thanks 

O and it will be a AMD X2 5200 2.7GHz, sorry.


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## Mussels (Sep 2, 2008)

coolermaster PSU's are fairly crap, to be honest.

there are four major areas it could be spread over. main ATX 24 pin power, 4/8 pin optional CPU power, Molex power plugs (HDD's etc) and PCI-E video leads.

With two rails, its really upto the PSU maker what goes where.


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## johnspack (Sep 2, 2008)

I'm not happy with my coolermaster 650,  it's choking out my 9800gtx.  Get a corsair tx750,  4 8 pin pci-e,  60amp 12v rail.....  and cheap,  I'm getting one!


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## Melvis (Sep 2, 2008)

Mussels said:


> coolermaster PSU's are fairly crap, to be honest.
> 
> there are four major areas it could be spread over. main ATX 24 pin power, 4/8 pin optional CPU power, Molex power plugs (HDD's etc) and PCI-E video leads.
> 
> With two rails, its really upto the PSU maker what goes where.



Yea i know, but there ok for this budget machine, my brother has two of the same case/PSU, run fine. But dont use a 8800GT tho.

It will be using the 4 pin power connection.

The rails i think a CPU runs off, is the 3.3V 22Amp / 5V 25Amp, total watts out put of 165W. I just need someone to tell me that it runs off that 165Watt rails^

Thanks again.


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## JC316 (Sep 2, 2008)

For a budget, get the epower ZU-550W unit. Very good quality.


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## johnspack (Sep 2, 2008)

Actually,  the cpu and the video card draw from the 12v rails....


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## Melvis (Sep 2, 2008)

johnspack said:


> I'm not happy with my coolermaster 650,  it's choking out my 9800gtx.  Get a corsair tx750,  4 8 pin pci-e,  60amp 12v rail.....  and cheap,  I'm getting one!



lol ummm im trying to get a ok case/PSU as in total cost around $120 so the 750 is WAY out, thanks anyway.


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## Melvis (Sep 2, 2008)

johnspack said:


> Actually,  the cpu and the video card draw from the 12v rails....



They do? bugger 

Guess ill have to get a different low cost PSU then =/

Thanks dude


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## johnspack (Sep 2, 2008)

well,  concentrate more on the psu than the case to start,  the psu is the building block of all systems,  a poor one will hurt the system....


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## Mussels (Sep 2, 2008)

Melvis said:


> They do? bugger
> 
> Guess ill have to get a different low cost PSU then =/
> 
> Thanks dude



almsot everything is on 12V rail these days.

CPU draws from 12V and 3.3V, ram from 3.3, video card and hard drive 5V and 12V. 12V is where the most power is drawn from these days.


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## candle_86 (Sep 2, 2008)

Mussels said:


> coolermaster PSU's are fairly crap, to be honest.
> 
> there are four major areas it could be spread over. main ATX 24 pin power, 4/8 pin optional CPU power, Molex power plugs (HDD's etc) and PCI-E video leads.
> 
> With two rails, its really upto the PSU maker what goes where.



mine has one rail on the 24pin and 4pin plugs, the other rail is on the molex's. I would assume this to be common myself


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