Any true multi rail PSU (w. over current protection) available for high-end systems?

[Jonesy1500]

Hi,

I’m new here and also very new to the PSU world, so I hope you’ll bear with me.

I know the conventional wisdom is that you should get a single rail PSU for a high end system, but I’m considering getting a multi rail PSU in stead because I’d like the improved safety they offer. (From what I understand multi rail PSUs have over current protection that will shut down the system if a dangerous amount of power is used.)

So I would like to know if there is a multi rail PSU out there that could run a system with a Q6600 CPU, a Geforce 8800 GTS GPU, 2 HDDs, 1 optical drive, 2 GB DDR2-800 RAM, and 1-2 PCI sound cards. (Preferably one that is modular and doesn’t cost not a lot more or make a lot more noise than the Corsair HX620 that I will otherwise get.)

Also, do you think it’s silly of me to want a multi rail PSU or do they in fact offer improved safety? A guy on another forum told me that ”almost” short circuits in PCs with a single rail could result in high voltages that could cause your computer components to melt and catch fire. That sounds like something I’d like to avoid happening, even if I’ll have to pay a little extra for a PSU. What do you think?

(You should know that I’m a first time builder, so there’s a not insignificant risk that I will screw something up that will cause a short.) :)

Hope someone will reply.

Cheers.

[Jonesy1500]

I just read about the Thermaltake Toughpower 750 - do you think it could run the above mentioned system? (It is truely multi rail w. OCP, right?)

Cheers.

[madmat]

"Almost" short circuits? Is that like being "almost" dead or "almost" pregnant? I hate to say it but that's just about the silliest thing I've heard of. Yes, it is possible to draw too much current through a single wire and melt the wire but it's not going to cause the voltages to spike and if it did the OVP (over voltage protection) would kick in and shut down the PSU.

Now, the only way this would occur is if the user or builder (if they're not one in the same person) were to do the "Christmas tree of doom" type wiring and use a bunch of Y's to hook up a buttload items to a single molex. If the PC is properly wired then the risk of it happening is next to nil. For what it's worth, a 20A rail similarly overloaded would melt the wiring just as quickly as a 115A rail as long as the load never exceeded the 20A needed to kick in the OCP. 18A or 19A would fry a single 12V wire and still remain under the OCP limit so a multi rail PSU is no more idiot proof than a single rail unit is unless the person is a complete and utter idiot.

[jonnyGURU]

Maybe this is a good time for me to shill the BFG 800W? ;)

[Jonesy1500]

Thanks for replying, Madmat. From what I understand he meant a short where there is some resistance (as opposed to a ”direct” short with no resistance) so that the current wouldn’t get so high as to trigger the OCP (or whatever it’s called on a single rail) and shut down the PSU.

You said:

Yes, it is possible to draw too much current through a single wire and melt the wire but it's not going to cause the voltages to spike ...

Wouldn't a melting wire be a bad thing in self, and likely cause fire/damage to other components? :confused:

Anyway, are you saying that the TP 750 wouldn’t really be safer than the 620HX?

By the way, does the TP 750 still have buzzing issues (or other issues) or have they been fixed?

I guess what I’m asking boils down to: Should I get the HX620 or the TP750? They cost about the same in my area, so my only concerns are safety on one hand, and whether it will get the job done without annyoing issues on the other.

Sorry for these questions that must seem extremely noobish to you guys. :)

[Per Hansson]

If you get a real short in a PSU it will shutdown (well if it has OCP but all decent PSU's does)

With real short I mean a metal to metal short

if you get something with resistance, say your GFX card fails all of it's caps in a semi short mode (so they still have resistance but are shorting to ground) you will on both PSU's be pulling enough current to melt the cables but most likely not trigger the OCP

That is to say if you are pulling 20aH through a single 12v cable on either PSU the cable will melt and the OCP will not kick in

Get a ampere meter and measure your computers max draw and install a fuse that is just barley above this if this really worries you

Just don't forget to do it to any other electric appliance in your house

And by now if you haven't figured out I am ironic here at the end I apologize :D

[Marc_pcgs]

Your rig will be just fine with a 520hx, in case you want to save a couple of bucks.

[Jonesy1500]

Thanks Per (and Marc)

But if the cables will melt with both a single and multi rail PSU, then what good does it do having a multi rail? Are you saying that a multi rail PSU isn't really safer than a single rail?

Hej då. :)
J

[Per Hansson]

Yes, multi rail is (according to most PSU manufacturers and hardware sites) just a stupid idea really

Most PSU's that say they are multi rail only do so for marketing reasons (else they would be in violation of the ATX spec so could miss out on a large OEM purcache for ex...)

If I'm not mistaken the multi rail req is being taken out in an upcoming ATX spec? (I could be wrong, just thought I read it somewhere..)

[madmat]

Actually it's not going to be taken out, it has been. It's still there as a recommendation but not as a requirement.

[Jonesy1500]

Okay thanks Per.