Dual 12v rails....Still bad news..

I'm sure This is going to stir up some dust...

A buddy of mine bought the Antec TRUEPOWERII TPII-480 BLUE ATX12V 480W Power Supply which died yesterday due to an overload. Thinking having Dual 12v rails would be better. Think again! I started to explain to him how that it is not and that your main +12v rail was still very low (18A) to be able to handle all of his stuff. 18 Amps is 216Watts of power and is about average for a 400Watt power supply.

The outputs are as follows:

+3.3V@30A, +5V@38A, +12V1@18A, +12V2@18A, -12V@1A, +5VSB@2A

According to Antec the second +12V2 rail is for the CPU only. The four pin connector has an 18amp limit! WHAT?!?!?. What a waste! So each 12v rail can achieve 216Watts of power... voltage x current = watts

With today's CPU technology, power consumption is the thing of the past. Having a 18 Amp 12 rail is pointless. Maybe a 5Amp 12volt rail would be better, then increase the main 12 rail to 30 AMPs.

Why would anyone want to have two 12 volt rails to begin with? If one drops below 12 Volts the system takes a dive anyway.. Now you just have two points of failure instead of one.

I'm a firm believer of one beefy 12volt rail, like my Antec True 550. 12v @ 30 Amps. 360 watts on the 12 volt rail..Now thats power.

Joeteck

I think there's still a place for dual rail power supplies like the fortron 500w and the seasonic s-12 600w. They're adequate for all but the most power hungry systems and are therefore excellent for the average user.

You'd need a pretty monster setup to even begin to use that much amperage. Check out the chart:

http://www.xbitlabs.com/articles/other/display/bluestorm_3.html

I just wanted something quiet and effecient with a 3yr warranty and NOT an Antec TPII (noisy!)and didn't mind dropping ~$140 in the process. I didn't hesitate to get the S12-600 after reading reviews even though it is WAY overkill for my current system.

Probably though, Prescott based Pentium D dual core CPUs will start to run dry of power at high overclocks on many dual +12v supplies. For this reason, PS units like the PCP&C 510 and OCZ 520 still have a large place in the OC arena.

Shane

Woodchuck69, that's a great example and proves that having dual 12 rails is pointless. It is a cost that is not necessary. If you add both 12volt rails, it does not come close to a 400watt power supply requirement. Thanks for proving my point.

Joeteck

Joeteck said:

Woodchuck69, that's a great example and proves that having dual 12 rails is pointless. It is a cost that is not necessary. If you add both 12volt rails, it does not come close to a 400watt power supply requirement. Thanks for proving my point.

Joeteck

Click to expand...

If your talking monetary when you say "cost" then I'd have to disagree. Not all dual 12V PSU's are expensive, many are a bargin. If that's not what you meant, then disregard this message.

The bar chart does not show the actual power consumption, so I took the liberty to put them in a numeric value for all of us to see. I did not do the +5 or the +3.3, since that is not what is on trial here. The numbers are in watts unless noted.

AMD 64 2.8ghz
--------------

Test +12V1 +12V2 Total Amps/watts with one rail
-----------------------------------------------------------
WINXP 43.2 21.6 5.4/64.8
S&M 43.2 76.8 10/120
BurnK7 43.2 74.4 9.8/118
3Dmark 80.4 58.8 11.6/139.2
Doom III 76.8 55.2 11/132
-------------------------
Pentium 4 4.0Ghz
----------------
WINXP 44.4 46.8 7.6/91.2
S&M 45.6 130.8 14.7/176.4
BurnK7 45.6 124.8 14.2/170.4
3Dmark 81.6 109.2 15.9/190.8
DoomIII 76.8 106.8 15.3/183.6
--------------------------

We can see that Intel is not the way to go for a gaming rig. The current / wattage requirements surpass AMD. From the look of it, a good 450Watt with a single 12v rail will do just fine for an AMD box.

Besides following the latest standard that Intel is promoting (ATX12V v2.2).

There's a safety concern via UL about too many amps on a single output. Essentially they're afraid of things frying. Most would say this is a bad thing.

Might want to check out http://www.silentpcreview.com/article265-page3.html. The whole article is about the power draw of 6 different systems. Pretty much you're right 18A on 1 rail right now probably doesn't make a lot of sense, since the most they could draw off 12V2 was 11A.

Another reason is to increase the stability of each 12V output so that neither of them flucuates as much. Typically considered a good thing.

However I'm surprised your friend was able to overload 12V1, unless of course his motherboard isn't making use of both 12V outputs in which case he was pretty screwed no matter who's dual +12V PSU he was using.

AntecRep said:

... in which case he was pretty screwed no matter who's dual +12V PSU he was using.

Click to expand...

I think that was rather his point.

I know the advantages inherent in dual rail supplies and expect them in time to be more capable than they are now. It does take extreme Prescott or Pentium-D action to overload an 18A CPU rail, but it can be done. The single rail supplies rated for 33-36A drive these loads successfully. And as the original poster alluded to, a late-model 30A TP550 will drive them with authority also. I've seen a TPII-430, rated for 31A of 12V output, fail to get windows loaded on a Pentium-D.

In time I expect to see multi-rail supplies standard and refined to the point that single rail supplies will seem awkward. But at present there are indeed loads the users here can honestly encounter that are better driven by single rail supplies, ATX12V2.x be damned. I respect Intel's expertise and trust their judgement, but it is possible to live far enough outside the PC norm for this particular credo to be limiting at this juncture.

I just wish that the dual 12v rail supplies be a little more useful. If the 12v2 is for the CPU only, then make that 13 to 15 amps. The 12v1 make that 25Amps or higher. I can see this being a better choice and then I would buy a Dual 12 rail supply. I find it rather more of a marketing ploy, rather than a useful power supply. I disagree with having too much load on a 12v rail. If it was designed to do it, then there will never be an issue. Case in point. I have an Enermax 465. (430 Watts) The 12v rail is 24Amps (5 year old model). I have a geforce 6800GT o/ced to an Ultra w/NV5, AMD 64 3500+, 1 gig of PC4000 RAM, (3) 7200 RPM drives, (2) CD/DVD drives. No problems at all. If I had any Dual 12v rail power supply with less than 24Amps, the power supply would die!

Why cant they make a switch where you can combine the outputs if you want to a single rail rated at both amps added together? I bet there is a way to mod the PSU yourself but you would void the warrenty. You really shouldnt have to though.

I am glad to read this post and be made aware of the problems with next generation pentiums and current dual rail designs. Some said AMD do better then Intels. Are current Dual rail PSUs enough for next gen of A64 chips? X2s and the like?

JT

JTanczos said:

Are current Dual rail PSUs enough for next gen of A64 chips? X2s and the like?

JT

Click to expand...

Definatly.

hahaha, this is some thread. i'm of the opinion that dual 12v rails is silly, but i think the idea behind it is that if you have a lot of optical drives, hard drives, video cards etc you wont be taxing the rail powering the cpu.

Joeteck said:

We can see that Intel is not the way to go for a gaming rig. The current / wattage requirements surpass AMD.

Click to expand...

that's hilarious.

edit: by the way, i'd like to see you prove that dual rails was at fault. probably just a faulty unit.

I just bought another Enermax 465 just a few days ago... This one they changed the 12v rail to put out more. The new one has a 33Amp 12V, my older one has a 24amp rail. I'm just glad to see that I'm not the only one who sees that a dual rail power supply is pointless.

JTanczos said:

Why cant they make a switch where you can combine the outputs if you want to a single rail rated at both amps added together?

JT

Click to expand...

the new tagana are like this
the 480w

the 530w

and can i know a thing about my enermax EG495AX-VE (W)SFMA(485W)

it have 2 12v @18..

here
so which 1 is for the cpu..

Keep in mind that your CPU is not running at 12V. If you regulate that 200+ watts back down to say, 1.50V, allowing for the regulators efficiency, that's over 100 amps available for the processor(s) alone. In my dual rail supply, using a clamp-on DC ammeter, it appears all the CPU power is delivered through that 4 pin plug (two yellow, two black wires). The other rail supplies the power for the other 12V needs in your system.

Hoot

The Tagana power supplies confuse me a bit. In both spec sheets, it show 12v1/v2 to be 20A each, but show different Wattages... I would not trust that brand...

Also, on the Enermax web page, if you look closely, there is no difference between the 375 to the 495 in terms of Amps on the 12v rails.... The 375 will perform the same as the 495... Sucks don't it?? The 495 seems better, but the 5V and 3.3v rails have been increased which is not needed at all.. Go figure... Again, the dual 12v design needs more tweeking..

And yes. The power supply did die, in fact, it took out the 6800GT, mobo and CPU due to an overload.. 18 Amps just could not do it... Just wait till PCI-e goes mainstream, the Dual 12v Rail power supply will be history...Trust me..

The 6800GT can draw around 100 watts by itself.. The ultra hit in around 125 watts. Thats 9 to 10Amps just for your video card!!! And about 20 watts on the 5v rail..

That leaves only about 8 Amps for everything else, Mobo, CPU, Hard drives, CD/DVD drives, etc........ hahahahahahahaha!

I hope every see's my point.....

Just wait till the dual core CPU's hit..... Holy wattage!!!

Actual e-mail to Enermax!

From: <[email protected]>
To: <[email protected]>
Subject: Dual 12V rails Stink!!
Date: Sun, 11 Sep 2005 00:40:00 -0400
MIME-Version: 1.0
Content-Type: multipart/alternative;
boundary="----=_NextPart_000_0026_01C5B669.579374F0"
X-Priority: 3
X-MSMail-Priority: Normal
X-Mailer: Microsoft Outlook Express 6.00.2800.1437
X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1441

This is a multi-part message in MIME format.

------=_NextPart_000_0026_01C5B669.579374F0
Content-Type: text/plain;
charset="iso-8859-1"
Content-Transfer-Encoding: quoted-printable

Dual 12v rail supplies stink!! Your Single 12v rail solutions are better
than your dual. I'm surprised your engineer department can't see
that...Ding-bats.. I should take over your R&D an make a real power
supply that will make you millions!!

Try this on for size!! This e-mail will be proof.

One 12v rail for video card(s) 24A
One 12v Rail for CPU 18A
One 12v rail for Mobo (20pin) 33A
One 5V rail 30A
One 3.3V rail 30A

Do this, and you'll have the ultimate Power supply around!!=20
Everyone will be copying you!!
Guaranteed!!

Read my post.... http://www.ocforums.com/showthread.php?t=3D409472