More or less rails on a PSU?

[Reloadron]

Originally Posted by Lead Head

Yup, The Enermax 1100 Watt(?) PSU, has 5 (i believe?) 12v rails, and two output transformers, but still 3 feed of one, while the other two feed off the other. Ultra on the other hand, with their new OEM, were seeking to create a 2KW PSU, they actually managed to do it with two 12v transformers, for a total of 150 AMPs of 12v power(its actually possible to do basic welding with that kind of amperage!) Although, it was listed as 1 rail, it was two rails, with each 12v transformer per rail, still adding upto 150 amps. UL did not approve the PSU, because it would draw over 2200 Watts from a socket, while most home sockets can only supply upto ~1700-1800 max. Ultra resent to UL as a 1600 Watt.

That's another good point. I read a little about the 2KW things. I want to think they resembled a suitcase. :)

Sooner or later something has to give. They will simply run out of room in the box. The form factors of PSU chassis have just changed a little with some units getting longer. Sooner or later they have to make a change in these boxes to accomodate the guts.

Maybe just an independent unit connected to the PC with massive cable?

Next, the service available in an average residence. Typical US residence is 120 VAC 60 Hz with 15 or 20 Amp service. A 2 KW PSU under full load could easily exceed that.

Ron

[Elysium]

So, more or less rails on a PSU?

The more power, the more rails??

[One4yu2c]

Yellowhello, get the Silverstone Olympia 650w unit. To quote myself when I reviewed it:

"Running two 8800GTS videocards and an overclocked processor with a moderately high vCore, the OP650 just would not budge. In fact, the rails ran tighter than any PSU to ever come through HardwareLogic's test bench, and while the price point puts this power supply above comparable models, we'd easily consider it to be best in class based on our testing."

OCZ has the better bang/buck, and their GameXstream series (rebadged Fortrons) are excellent units, but I was even more impressed with the Olympia.

[Elysium]

Yellowhello, get the Silverstone Olympia 650w unit. To quote myself when I reviewed it:

"Running two 8800GTS videocards and an overclocked processor with a moderately high vCore, the OP650 just would not budge. In fact, the rails ran tighter than any PSU to ever come through HardwareLogic's test bench, and while the price point puts this power supply above comparable models, we'd easily consider it to be best in class based on our testing."

OCZ has the better bang/buck, and their GameXstream series (rebadged Fortrons) are excellent units, but I was even more impressed with the Olympia.

Thanks for the advice, One4. I'll be going with the Silverstone.

[Tyreal]

Here's some more information for you.

Originally Posted by PC Power and Cooling

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.

Power Supply Myths Exposed!

[Death_blooms]

Originally Posted by Panda Man

>_> I've never even heard of PCP&P until this thread.

me neither.

[Zambini]

I like HIPER's modular 580W PSU (the one I have) cuz it has removable cables. That way the whole problem of cramped space caused by multiple rails = gone, and they can still stick a fatty on as one of the main ones.

[gvblake22]

Originally Posted by Zambini

I like HIPER's modular 580W PSU (the one I have) cuz it has removable cables. That way the whole problem of cramped space caused by multiple rails = gone, and they can still stick a fatty on as one of the main ones.

Just to clear things up here, multiple 12v rails on a PSU does not cause it to have more cables. It is purely how the internal components and circuitry of the unit are set up, not how many physical cables are coming out of it.

[Zambini]

Originally Posted by gvblake22

Just to clear things up here, multiple 12v rails on a PSU does not cause it to have more cables. It is purely how the internal components and circuitry of the unit are set up, not how many physical cables are coming out of it.

Oh. Could've fooled me.

'course I dont know anything about PSUs besides how many jiggawatts it has.

[Gig-O-Ram]

Originally Posted by Panda Man

This can easilly be debated. IIR, I read that one of the main reasons for Dual rail in the first place was because once you get over 35A on the 12V rail, the higher the tendency for the PSU to blow.

I've been reading more of that piece on PSUs in CPU magazine, and this made me recall the thing they mention that there was a limit to no more than 20A on any one 12V rail.

I also saw a guide on how to go about figuring out the exact current needs for given components - which I did not do when building my current setup. I chose my PSU based on the fact of it's rated wattage, and didn't take into account (or even realize) that my chosen video card actually needed a 6 pin plug, and got lucky that it had enough cables for the four power connections required by my board, as well as cables for everything else.

When I go to put my next system together (at some point), I'm gonna take the time to see what all the parts need, and make sure I don't just "get lucky", and then I'll see if I even need to go with a multi-rail, but somehow I think I'll choose a powerful single rail.

And to quote a few others, I always thought PCP&C was not as high up on the PSU ladder as some say they are. I thought they were a lesser brand compared to OCZ, Enermax, etc. I guess I was wrong.