Quick 12v Rail Question

[hennessy1]

I currently own a pcp&c psu
http://www.pcpower.com/power-supply/turbo-cool-1200.html

I want to purchase this psu from thermaltake
http://thermaltakeusa.com/Product.aspx?C=1245&ID=2061#Tab1

My question is the 12v rail on the pcp&c model is that better then the 4 12v rails on the thermaltake model even though those add up to more then the thermaltake model?

 

[lehtv]

I would prefer a single-rail design, especially if the total 12V amperage is more than on a quad-rail PSU. Then you don't need to worry about amperage limits within each rail. It's just simpler.

Are you sure you want a Thermaltake though? And are you sure you need 850W? It would be worth checking if you could get a Corsair, Seasonic, Antec or XFX equivalent.

 

[hennessy1]

Reason I had chose thermaltake was because I have used them w/o issues before. I tend to get attached to brands that don't crap on me. I pull atleast 1000w from the wall according to my ups display. That is without my planned upgrades I wanted to do.

 

[lehtv]

That's quite a power draw. If you pull that much from the wall, an 850W PSU isn't enough. You don't want to strain a PSU to 100% - the optimum is around 60%, but close to 80% is still acceptable. I'd recommend a 1.2kW PSU, e.g. Antec HCP-1200, Corsair AX1200 (7 year warranty) or Enermax Maxrevo 1350W. They're all about the same price and very high quality 80+ Gold products.

What's the hardware that draws all that power?

 

[hennessy1]

3 overclocked gtx580's, intel 980x, several hard drives, add-on cards and 24gb of ram. Is what I currently have installed. So single rail is better because you can not tell what rail each component is using on a multi rail psu?

 

[lehtv]

EDIT: Oh excuse me i realised something. I did click on your links before but somehow I thought you linked to an 850W Thermaltake. I must've had another tab open or something. That Thermaltake 1500W is a beast of a PSU, but I think it's more than you need, unless you're planning quad-SLi. Also, at the wattage your drawing, I would want all the efficiency I can possibly get so I'd go with 80+ gold.

--original:

Yeah, that's one reason. Keep in mind that I'm not a professional, but to me single-rail is obviously a simpler way to build a PSU. Multi-rail is kind of a coin with two sides... On one side, a high quality multi-rail PSU will distribute the power to the cables in such a way that you can't saturate any of the rails no matter what hardware you connect. It's a safe design if done properly. On the other side of the coin, you can have a low quality PSU with multiple rails that are not sufficiently overspecced. And so, if you attach the cables to something that's more power hungry than the PSU was intended to be used with, you're in trouble.

But a good single-rail design will have enough +12V ampers for any combination of hardware that doesn't exceed the rated wattage of the PSU.

Antec HCP-1200 is actually an eight rail PSU, each rail has 30A max. That doesn't mean you can load all rails at 30A simultaneously - it's rated at 99A for all combined. I'd assume the cabling is designed in a way to make saturating any of the rails impossible. In this case, I wouldn't really take the multi-rail design as a minus, it's a very very high quality unit.

Enermax Maxrevo 1350W is a 6-rail PSU, 30A on each. Again assuming the cabling is designed in a way to make saturating one rail impossible.

AX1200, on the other hand, has a single 12V rail rated at 100.4A, enough for your purposes.

 

[hennessy1]

I was thinking of adding another card for quad-sli. I did see the current pcp&c psu has I believe 115a. The thermaltake has 160a with 30a being the lowest one on two rails and 50a being the highest. So your saying that the psu would load balance the 12v rails. I see that the gpu connections would have atleast 100a to their own and the motherboard, cpu, and hard drives would have 60a to themselves.

 

[lehtv]

No, the Thermaltake doesn't have 160A total. 30A and 50A are just the limits within each respective rail, but for all combined, it's less than that.

http://thermaltake.com/products-model.aspx?id=C_00001781 The total wattage of +12V is 1320W, which equals 1320W/12V = 110A.

Silverstone Strider 1500W is a good alternative but it can do the same 110A on +12V total. It's an 8-rail unit with 25A on each. The sum of each rail is 200A, compared to 140A for the Thermaltake, making Silverstone's power distribution probably safer.

The GTX580 will use a bit over 20A at TDP limit at stock speeds. So a bit over 80A absolute max at stock, leaving plenty of room for your CPU and other 12V parts. But it's unlikely that any application will stress all the GPUs to 100% simultaneously, don't you think? So even with the cards heavily overclocked, I think you're safe.

 

[hennessy1]

I have the two compared side by side with each other. I am not as well informed about this as you are but looking at it the 12v rails are the only difference but with the same amount of wattage on them how does that work exactly? Is it just taking the same amount of power and just dividing it differently?

 

[hennessy1]

I also did a little looking on thermaltake's manufacturer's website and their psu seems to have different specs then the ones listed on thermaltake.

 

[lehtv]

I have the two compared side by side with each other. I am not as well informed about this as you are but looking at it the 12v rails are the only difference but with the same amount of wattage on them how does that work exactly? Is it just taking the same amount of power and just dividing it differently?

The +12V rails combined are rated for the same amount of total wattage or amperage. Whatever the current limit within each rail is doesn't enter that equation. I think the current limits are not recommendations, but "hardwired" - if exceeded, Over Current Protection will kick in and shut the PSU down safely (I'm not a 100% on this.)

The number of rails a PSU has is just the power distribution design. With one rail, there's only one way to overload the +12V. Obviously. With more, you need to only overload one of them and the protection will kick in. This obviously affects the way the manufacturer decides to split the power between the rails - what components or cables are designed to use what rails. So yes, with a particular set of components that you connect to the PSU, it will draw the same amount of power overall, regardless of number of +12V rails. But the power will be distributed from the PSU differently.

If you're really on the fence about which PSU to get and you want to find out exac answers to your questions, I would suggest contacting an expert on the matter, e.g. email to JonnyGuru or Hardwaresecrets or some other reliable PSU review site.

I also did a little looking on thermaltake's manufacturer's website and their psu seems to have different specs then the ones listed on thermaltake.

It may be an older version of that model you're looking at on the OEM's site. What is the OEM btw? Silverstone 1500W is manufactured by some company called Enhance. Never heard of them before, but JonnyGuru's review of the PSU was very positive (9.7/10).

 

[hennessy1]

Channel Well Technology is the OEM.