Archived from groups: alt.comp.periphs.mainboard.asus (
More info?)
Very thorough and informative as always! Thanks so much. btw, I have a
truepower 550w psu.
"Paul" <nospam@needed.com> wrote in message
news:nospam-0505050035280001@192.168.1.178...
> In article <CaidnV_NtNvprOTfRVn-vA@speakeasy.net>, "PJ"
> <pjNOSPAM@hotmail.com> wrote:
>
> > I only have one 6800gt card in my system right now and it is hooked up
> > directly to the PSU. Does it hurt to have the molex power on the board
> > connected to the PSU as well or should I leave it disconnected until I
get a
> > second card and run in SLI mode?
> >
> > Thanks,
> > Paul
>
> Generally speaking, additional power plugs can be connected
> without causing a problem. It might not make the system any
> more stable than it already is, but it should not hurt anything.
>
> An issue to consider, is what kind of power supply is being
> used. I can see at least three types making the rounds.
>
> The PCP&C Turbocool, is an example of a pre ATX 2.0 spec
> power supply. It has all of its 12V power coming from one
> output winding. With this power supply, there would be no
> concerns with using additional power plugs like the EZplug.
> 12V is 12V is 12V.
>
> The next type of supply, is the ATX 2.0 type supply. It has
> two outputs, called 12V1 and 12V2. You can get a spec here:
>
>
http://www.formfactors.org/devlist.asp?FFID=1&CatID=2
>
> On the ATX 2.0 supply, the processor is powered by 12V2, and
> the rest of the 12V loads (motherboard ATX 24 pin, disk drives)
> run from 12V1. Again, in this case, it is safe to plug the
> ATX 24 pin and a disk drive connector into the motherboard,
> because they both run from 12V2 and are at the exact same
> voltage. (Note that 12V1 and 12V2 are not at exactly the
> same voltage, but neither are those two rails joined inside
> the motherboard, and that is why the ATX 2.0 supply can work
> in the first place, without burning anything.)
>
> The third kind of power supply I've run into, is the
> one with four 12V circuits. The Silverstone is a recent
> addition to the Nvidia SLI certified power supply list.
> The PCP&C turbocool 850W (just announced) also has this
> feature. I don't know which standard defines this supply
> class, whether it is SSI, GES or something else. (If
> someone knows what standard is used for these, and has
> a URL, I'd appeciate it if you would post it.)
>
>
http://www.silverstonetek.com/products-65zf.htm
>
http://www.linuxhardware.org/article.pl?sid=05/04/15/1742246&mode=thread
>
> Here's how the SilverStone's 12V lines are divided, according
> to the lunuxhardware review (as Silverstone didn't feel
> we needed to know this info):
>
> +12V1: CPU0 13A/18A
> +12V2: CPU1, SATA, Motherboard 18A
> +12V3: Motherboard, PCI-Express 16A
> +12V4: Molex Connectors 8A/13A
>
> Now, my first comment about the above info, is it doesn't look
> right. The word "Motherboard" should only appear on
> one line above, not two. That would be stupid.
>
> Notice how in this case, that the Molex connectors are on
> 12V4, while the motherboard power is on 12V3. This is an
> example of a power configuration where I would _not_ want
> to connect the EZPlug. Since there are PCI Express power
> connectors, this would be a great supply for dual PCI
> Express video cards with their own 2x3 PCI Express power
> plugs, as the EZPlug would not need to be connected.
> The red warning LED will just have to light up your case
> with its warm red glow.
>
> The Enermax EG851 looks like it has quad 12V, as does the
> new PCP&C Turbocool 850, the Silverstone product above, and
> who knows what else. So far, I haven't seen enough detailed
> info on any of these products, to see exactly how the power is
> split between cable assemblies. If spending the big bucks
> for one of these supplies, I would want a diagram labelled
> with 12V1, 12V2, 12V3, 12V4 for each and every connector
> on the supply. Otherwise, if different 12V outputs are
> connected together, loop currents could start to flow.
> I know some supplies have options to bridge rails like
> these together, but I don't know if these new quad 12V
> supplies have such an option or not.
>
> The only company I can depend on for this info, is PCP&C.
> They give good docs on their web site. The rest are hopeless
> when it comes to product details. (Since the PCP&C 850W is
> not shipping yet, the docs aren't on the site. I can't
> wait to see if PCP&C properly label their four 12Vx
> outputs.)
>
> OK. I just downloaded the Enermax EG851 from here:
>
http://www.enermax.com.tw/download/EPS_12V_English.pdf
>
> It looks like:
> +12V1: CPU0 (one half of the 2x4 connector)
> +12V2: CPU1 (other half of the 2x4 connector, also the 2x3 CPU connector)
> +12V3: Motherboard
> +12V4: ? Not stated. Maybe disk drive connectors ???
>
> So, this would be another supply, where I would not want to
> use the EZplug at the same time as the Motherboard plug is
> there. That is because, then 12V3 and 12V4 end up connected
> together. It would be really dandy if Enermax could write
> a decent manual that told us where 12V4 goes...
>
> Mixing a quad 12V power supply, with video cards having no
> separate PCI Express power connectors, looks like a bad
> thing, as then you really need the benefits of the EZplug.
> In a case like that (if you had some 6600 class cards for
> example), you would be much better off with a single 12V
> output supply, or a dual 12V output supply like any ordinary
> ATX 2.0 type supply.
>
> Seeing as the quad 12V output supply is really overkill anyway,
> avoiding it altogether is an even better option. In most
> normal desktop circumstances, you aren't going to be able
> to put any load on 12V2 anyway, so it amounts to only a
> triple 12V output supply. And, since the EZPlug cannot
> likely be used, the two video cards end up running off 12V3.
> Which means any power left over on 12V4 cannot be harvested.
>
> The quad 12V looks like it would be a good investment for that
> dual opteron dual x16 PCI Express server board that was just
> announced by Tyan.
>
> Paul
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