PSU's---2 x 12v---The Dual Rail Myth

[ChakkaSol]

Take a Tagan u22 for example. I use it as it has a trick. You can combine it's two rails into one with a switch on the back. It has a 30a total 12v output if you have it switched to single rail. Or if you select dual it is a 20/20 split. Tagan is a pretty good PSU maker. However you can see that it is only giving 30a total power output on the 12v rails no matter where the switch is set. So in split mode both rails will have to equal that number. That may be a 15/15 split or a 20/10 split or maybe something in between. I have seen folks have issues in split mode that goes away in single rail mode. So yu tell me what is going on then.

Tagan has a patent pending on this so we dont see this in other psus.  In my second rig, I have the tagan u22 set to a single rail setting.  I think at the time they made these dual rail was just coming out and Im sure they wanted to sell these psus in any flavor a consumer wanted.

But more to the point.  We have another major company coming out with 2 new huge single rail psus - Silverstone.  The first model is the 650w, 54a on the 12v rail:
http://www.silverstonetek.com/products-op650.htm

And the 1 megaton psu with 80a on a single 12v rail:
http://www.silverstonetek.com/products-op1000.htm

Now why would 2 major companies go back to single rail psus?  I was reading up on this and its cheaper to make than multirail psus plus they are finding that their is no safety issue with having so many amps on a single rail (like electrocution).

 

[Tiresmoke]

PCP&C also went back to Single Rail PSU's. Like I have said right along is that Split Rails are just marketing hype and they are taking your cash away for smoke and mirrors.

 

[Frankenputer]

ChakkaSol, your second link is the same as the first. I think this is the link you wanted for 1000W, megaton as you put it, PSU: http://www.silverstonetek.com/products-op1000.htm

 

[BG84]

ive been having trouble with my stupid dual rail psu lately,what do you guys think of this http://www.ocztechnology.com/products/power_management/ocz_gamexstream_power_supply-nvidia_sli_ready_ the 600w it has 4*18a rail. im not able to buy any single rail psu, if i take the ocz it would be at cost price, so get a really good deal, btw ive it seen on a crossfire 1900xtx runnin fine

 

[Rossoevo]

BG84

Here is a test report of the 700w version of that PSU.

http://www.jonnyguru.com/review_details.php?id=35

This is probably cheaper and does the job.

http://www.jonnyguru.com/review_details.php?id=30

 

[Rossoevo]

Some of you might find this interesting.

PSU Recommendations for High End Gaming PC's

http://www.jonnyguru.com/forums/showthread.php?t=103

 

[Frankenputer]

Some of you might find this interesting.

PSU Recommendations for High End Gaming PC's

Huh?  Is there supposed to be a link?

edit: Sure it's showing, now that you fixed it.

 

[Rossoevo]

Link showing my end !!

Frankenputer

You must have read the post before I realised the link was not there & fixed it,3 minutes later.

Try again.

http://www.jonnyguru.com/forums/showthread.php?t=103

 

[BG84]

this is what i found in my side http://www.diy-street.com/forum/showpost.php?p=687853&postcount=2 

 

[Rossoevo]

BG84

Dont know how that happened,just having one of those nights 

 

[BG84]

BG84

Dont know how that happened,just having one of those nights 

huh?

 

[ChakkaSol]

Guess what - Tiresmoke and Bas must have written the following for PC Power and Cooling...they have a myth link too:
http://www.pcpower.com/technology/myths/#8

PC Power states on their website:

8. ARE MULTIPLE 12-VOLT RAILS BETTER THAN A SINGLE 12-VOLT RAIL?
With all the hype about multiple 12-volt rails (ads claim that two rails is better than one, five is better than four, etc.), you?d think it was a better design. Unfortunately, it?s not!

Here are the facts: A large, single 12-volt rail (without a 240VA limit) can transfer 100% of the 12-volt output from the PSU to the computer, while a multi-rail 12-volt design has distribution losses of up to 30% of the power supply?s rating. Those losses occur because power literally gets ?trapped? on under-utilized rails. For example, if the 12-volt rail that powers the CPU is rated for 17 amps and the CPU only uses 7A, the remaining 10A is unusable, since it is isolated from the rest of the system.

Since the maximum current from any one 12-volt rail of a multiple-rail PSU is limited to 20 amps (240VA / 12 volts = 20 amps), PCs with high-performance components that draw over 20 amps from the same rail are subject to over-current shutdowns. With power requirements for multiple processors and graphics cards continuing to grow, the multiple-rail design, with its 240VA limit per rail, is basically obsolete.

PC Power and Cooling is once again leading the industry. All of our power supplies now feature a large, single 12-volt rail. The design is favored by major processor and graphics companies, complies with EPS12V specs (the 240VA limit is not a requirement) and is approved by all major safety agencies such as UL and TUV.

 

[BG84]

these guys at pc power rock 

 

[ex_forum_user_3]

Yeah, but they only state it recently, we have been saying this right from the beginning

In short, split-rails stink, single rail is the only good way to do it :lol_anim:

 

[Rossoevo]

Very true Bas

The PC Power & Cooling Turbo-Cool 1kW-SR was first marketed as a 3 rail version.

Only recently has it reverted to single rail.

 

[BG84]

got today my ocz 600w gamextream, seems decent, i wanted a single rail, but i bought this one for the ridiculous price it was sold to me. i wanted a single rail one, but too much headache to find one. and like i showed the link before, the guys at dfi claim that its theyre favorite psu for high end systems (?), i hope theyre right.... ill be running some benchmarks and see the difference. i hope im lucky this time with a multiple rail psu.....

 

[Hans]

Just an update on another psu-brand. Have a look here:
PSU comparison table: http://www.qtec.info/products/comparison.htm?mpg=PSU
Can someone tell me what to compare it with?
And then this:
http://www.qtec.info/service/warranty/
What do they mean by "carelessness"? Do you think what I think? Can someone explain this?

 

[Hans]

Ow, I'm so dumb somethimes ... this is not dual rail, but dual fan ...  :lol_anim:
Oh well, who cares? 

 

[BG84]

well it seems they only one psu left, where are all the rest?

 

[Hans]

Well, that's just the point: it seems that Q-Tec doesn't sell any psu's anymore and that, because of that, they stopped making them. This is probably the last one left in stock ...