Most Amps?

[Raptor9]

From what I've read, a new ATX12v board with a PCI-e card should get at least 20-25 amps on it's 12v rail. I've been searching for PSU's in the 350-400 watt range(anything more is overkill for me) that can supply that kind of amperage, but have been hard-pressed to find a unit. That said, are there any PSU's from reputable companies known for a good watt to amp ratio? If I understand correctly, it's the amps on the 12v line that really matter--is this true?

 

[wisdomtooth]

What I'm using. 22 Amps on the 12V rail.

Very high quality unit, also the quietest fan-cooled PSU you can buy. Recommended by Silent PC Review.

 

[AristoV300]

That looks like a quality PSU at a good price, even has Acitve PFC:thumbsup:

 

[Raptor9]

What about dual-rail PSU's? Are two 12v rails working at 15 amps the same as one at 30a as far as functionality is concerned? Does dual-rail mean that there are two physically seperate 24-pin cords, or is it still integrated into one? Also, how is the power distributed? In other words, if the motherboard, CPU and graphics card need 25 amps, can two 15 amp rails deliver the needed power, or is it not that simple?

 

[Painman]

26 amps on 12V rail - Enermax 350W EG365P-VE FMA

 

[FP]

i feel a long thread coming on...

 

[Algere]

Originally posted by: Raptor9
are there any PSU's from reputable companies known for a good watt to amp ratio?

There isn't a good (or bad) watt to amp ratio since wattage is the product of amperage, & voltage is fixed (non-changing). Watt to amp ratio will always be the same no matter what type of PSU you have.

VA or volts*amps = watts. In the case of 12 volts... 1A=12W, 2A=24W, 3A=36W, etc.

To your original question, if you meant amp/wattage to price ratio or vice versa, Fortron has a good price to amp ratio ($98/36A : $2.7 per amp) in the 500W+ range (single rail version is $10 more) & is generally known for having decent quality PSUs at attractive prices. The price to amp/watt ratio is probably better in the lower wattage range and on older PSU models.

Originally posted by: Raptor9
If I understand correctly, it's the amps on the 12v line that really matter--is this true?

Today's systems rely more on 12V power than in the past & everything else (5 & 3.3V) is adequate enough (in relation to a PSU's total wattage) on most if not all PSUs so I suppose it's true when it comes to what you're looking for in a PSU.

Originally posted by: Raptor9
What about dual-rail PSU's?

What about them?

Originally posted by: Raptor9
Are two 12v rails working at 15 amps the same as one at 30a as far as functionality is concerned?

Sort of but not quite. There's total amps (which is 30 in this case) and then there's usable amps (functionality). Depending on how a system & PSU is configured, a system can have access to as much as 30A or as little as 15A.

Originally posted by: Raptor9
Does dual-rail mean that there are two physically seperate 24-pin cords, or is it still integrated into one?

Still one & it means (generally speaking) half of a system's 12V load is on one rail, while the other half of the load is on the other.

Originally posted by: Raptor9
Also, how is the power distributed?

Depends what PSU brand & model it is. I've read/heard multiple configurations. Such as...

Config. #1
Rail 1: CPU (2x2 4-pin) & motherboard (20/24-pin)
Rail 2: gfx power (PCIe 6-pin/AGP 4-pin), drives, fans, etc.

Config. #2
Rail 1: CPU
Rail 2: motherboard, drives, fans, gfx power, etc.

Config. #3
Rail 1: CPU, motherboard, & SATA
Rail 2: gfx power, & 3/4-pin molex (fan, ATA drives, floppy, etc.)

I'd contact the PSU maker on specifics.

Originally posted by: Raptor9
In other words, if the motherboard, CPU and graphics card need 25 amps, can two 15 amp rails deliver the needed power, or is it not that simple?

It can but again it depends on the configuration of the system & PSU.