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Dual power supply cons

S

Slade

2[H]4U
Joined
Jun 9, 2004
Messages
3,099
What are the cons of running 2 power supplies?

What if you used a power supply connector like what coolermaster gives? I know the benefits would be having more power per say, more devices etc. I also suspect there to be cons, but being that I don't come from a heavy electrical background I'm quite curious.
 
There are a ton of ramifications to using dual PSU’s. If you use the “Search This Forum” tool you fill find tons of information on the subject. Type in “dual power supply”.
 
That didn't answer my question, I'm well aware of the benefits of having the ability to run "a lot of hard drives" or exotic cooling methods. I was hoping for a more technical minded answer than the typical "you can run lotsa junk with lotsa power!" minded answer Also, the topics rutured by that result (of which I was sure to look up before posting this, did not cover what exactly I am interested in)

What of the power modulation? What about the mobo having 2 power supplies attached to it via a connector cable? What cons would their be to the devices? Cons to the mobo? Is it "clean power" in a sense jury rigging such a setup? A tech guy was wiring up 3 power supplies to make a total of 1000W for a 3 terrabyte file server. We got into a quick discussion about why he went about wiring up 3 supplies, although the reasons behind it are questionable, but since I'm no expert I wanted a bit more explanation from one of the experts here.
 
Well, first things comes to my mind is uneven grounds. If the ground potentials between the power supplies are different (even though they shouldn't be, both attached to the case and all), you could have voltage going through quite a few lines it shouldn't.
 
I have done this before. Run daul Power Supplies,
It does help quite a bit.
I run 2 HDs, a DVD-RW, and a CD-RW on a 350 W PS
and my video card and MOBO are run on the same exact one. it is pretty efficent and it is a bit cooler. but there are risks.
I did it cause my friend Rob decided he had so many drives in there.
BUT! never run two PSs with such a great difference in the Wattage, and make sure both PSs turn on at the same exact time. try to set them far apart if you're going to do some serious gaming cause they will end up making each other hot. don't try any fanless PSs, (ones with radiators) they tend to do strange things.
Yeah, Rob sacrificed an old PC 2 months ago attempting this. it eventaully came down to him running a server on 2 PSs.
(4 HDs. 2 Optics)
(Mobo)
so yeah, it does help a little, it takes a load off the single PS.

edit: one more thing, you better hope your case is nice and bi with lots of cooling. and get out those wire ties cause alot of wires will need to be bundled for good airflow.
 
Slade said:
That didn't answer my question, I'm well aware of the benefits of having the ability to run "a lot of hard drives" or exotic cooling methods. I was hoping for a more technical minded answer than the typical "you can run lotsa junk with lotsa power!" minded answer Also, the topics rutured by that result (of which I was sure to look up before posting this, did not cover what exactly I am interested in)

What of the power modulation? What about the mobo having 2 power supplies attached to it via a connector cable? What cons would their be to the devices? Cons to the mobo? Is it "clean power" in a sense jury rigging such a setup? A tech guy was wiring up 3 power supplies to make a total of 1000W for a 3 terrabyte file server. We got into a quick discussion about why he went about wiring up 3 supplies, although the reasons behind it are questionable, but since I'm no expert I wanted a bit more explanation from one of the experts here.
Click to expand...

If you had bothered to look at all the relevant links you will see Ice Czar has written quite a bit about the “how too” the “what not to do” etc.

I was just trying to keep everyone from repeating over and over what’s already been covered so many times.

Ice Czar as well as gee have written paragraphs on the subject as well as referenced many other tech sites in order to answer just such a question as you posted.
 
No offense, but those stickies are for people buying PSU's... and I've gone through as much as I'd care and have time to read. I also searched as well for something specific, but no one really hit on the topic dead on, I've only found tidbits here and there but not a definite "here are the pros and here are the cons, and here is why it is or isn't a good idea" type of posting.

Most of the info when sifted out is not as obvious to the general public with a little knowledge. You know full well that assuming is dangerous especially when dealing with a device that can potentially hurt someone if one were to assume you could become an expert by trying to sift through the faq's currently around.

"off topic and potentially inflammatory"
normally I wouldn't ask anything remotely about electricity as my father was a very damn good electrical engineer, unfortunately due to a recent accident he's missing half a brain now and the one person in the world that could possibly answer anything about this to me is more or less gone now, so I come here hoping someone could shed some light and give me ideas for future projects I have in mind.

Please, I've already stated I've tried to find the answer via search, and through the faq's and google, but I haven't found the conceptual idea to tie together all the info because for lack of a better description, I am an electrical NEWB.
 
Othersider:

Would this also cause "dirty power" ie a 12 V that fluctuates >spec?

Kaiga:
Would a difference in "wattage" be a more serious problem than say a difference in load? If only the soft on switch was wired together, would a power supply running only fans/lights/drives and another running cpu/mobo/cpu cooling experiece the same problem?

What if they were shared ie 20 pin connector cable but with different loads 1 psu only had a weak load fans/lights cdrom floppy, and the other had the hdd/cpu/mobo?
 
Well eventually I'm intent on building a serious power rig. Depending on how the whole 64-bit/dual core battle goes (not sure who will be the cpu of choice by year's end) when the dust settles it could be back in intel's hands like when the northwood C series came out, or it could be in amd's hands with the fx series.

No matter who is the victor we have a crazy power scenario going.

Picture the needed power supply on this...
Dual core/64 bit CPU (I would say if it was intel on top, it would need A LOT of power)
High end full featured mobo (dual gigabit lan, onboard wireless?, firewire, USB)
2 GB DDR2 (granted it uses less volts and therefore less power than DDR)
6800 Ultra SLI (or maybe NV 50 24 pipeline sli? effetive 48 pipeline)
Some high end soundblaster with whatever sound specs it does 8.1 etc
DVD Blue ray writer
DVD Blue ray reader drive
300GB RAID5 (3 drives needed right?, it may be a boot drive, but its for boot/os/general apps)
300GB RAID5 (another 3? also because I like 2 "separate drives, 1 for boot/os, 1 for general storage)
Some crazed cooling solution to handle this baby overclocked, fans, lights/bling....

Given current trends and roadmaps, systems like specified above may become a reality by year's end/2006...

Would current/"announced for this year" power supplies even come close to supporting such a monster...? Is dual ps in the books for making a rig a reality...
 
Slade said:
Othersider:

Would this also cause "dirty power" ie a 12 V that fluctuates >spec?

Kaiga:
Would a difference in "wattage" be a more serious problem than say a difference in load? If only the soft on switch was wired together, would a power supply running only fans/lights/drives and another running cpu/mobo/cpu cooling experiece the same problem?

What if they were shared ie 20 pin connector cable but with different loads 1 psu only had a weak load fans/lights cdrom floppy, and the other had the hdd/cpu/mobo?
Click to expand...

oh yeah, I forgot to mention that. When you do daul PS, say good bye to the little soft on switch. Your PC is only going to turn on via the PSUs. and when you turn it on, turn them both on at the exact same time.
(!--NOTE: if you can, try to find a way to do a soft switch mod to get them both to work, that would be awesome.--!)
(starting to go caveman PSU setup.) Rob tried the soft switch and it doesn't work. what my friend did was, he went to a regular hardware store and bought one of those dual pull switches (ones with the bridge on it.) like you could find in your house's fuse box. he opened up both the PSs (note: this is when installation gets very difficult cause the power switch can bust. try to hold them both equally.)and intstalled that big pull switch.
P1010055.jpg

Bridge switch.(from fuse box) get one of these except one long enough to go the distance between both PSUs.
I haven't done this yet though, I just switch both on at the same time manually.

Dirty power won't be much of a problem since you're not working each psu so hard. you just need to make sure you take care of them, a small difference in your V wont be much of a problem ie your 12 drops to 11.5. when you drop lower than that, then you need to do something about it.
A difference in load would be more of a factor than wattage. you should try to even out the load on both PSUs. Dont run your HDDs and CPUs and fans on one PS and then run the rest on the other. Run your Floppy, optics drives, and HDDs on one, and run fans, LEDs, CPU and mobo on the other.(just designate one for your whole mobo setup on one and your drive setup on the other.) dont let one have a bigger load than the other. and when it comes to PSU wattage, try to keep them the same. dont go out of the 200W difference range. if you run two with diff. wattage, run the one with the most wattage on your MOBO setup. and the weaker one on your drive setup.

Bassically here are the pros and cons:
pro
  • more efficient power
  • no power dropping problems
  • better load stats

cons
  • goodbye soft-switch(unless you find a way to make it work.)
  • turning both psu's on at the same time
  • cooling will be more of a factor in your pc
  • airflow due to wires
  • you might need to get a bigger case or modify the one you have in order to mount that second one in there.
  • more wires to deal with
  • depending on the case you might need to sacrifice a rear fan to get it in there.

Drugfranbs said:
With all the risks, you may as well get a Nuclear Reactor in there
Click to expand...

no, if you install it properly, you wont need to take the risks.

this installment for Rob took him roughly 9 hours, but thats cause of all his experimentation(think of his living room as the PC PSU lab for the day.)
his official installment (ie case cutting, wiring, fabrication, screws etc.) took 4 hours
after taking all his advice, and telling me how to do it, it took me roughly 4 too.

If you want the how-to on this, or any questions, e-mail me and I will be willing to type one up for you. I dont have any pics of it though.(shitty cam) but I can do some detailed instructions. I'm sure it might be self explanitory for you.
 
one more thing:
cases with the extra PSU slot would also be ideal. I just didnt have the $$$ to go and buy on off the evil internet. I see in BillR's post those links he provided had more info on it too.
 
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