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2 Power Supplies..Dangerous?

J

Jiggaman2576

Limp Gawd
Joined
Oct 27, 2004
Messages
377
I've been doing some reading and I just want to make sure I can do this. I have 9 hard drives in my PC, plus all the other junk in my signature. I just got an X1900XT which I flashed to an XTX and I have been overclocking the crap out of it. I've run into a wall though. Turns out running 9 hard drives, an overclocked AMD X2 3800 at 5000 levels (2.6ghz) with 2GB of ram, an X1300 (3 monitor setup now) and a sound card is kinda taxing on my OCZ 600 watt powerstream. I've just ordered the 700 watt and I'll have it Monday. I figured why not use both together to make it easier on each.

I have 2 power supplies right now but I only run fans/lights on the 2nd PSU, oh and the water pump. It doesn't have much of a load on it. What I want to know is, if I replace that with the 600 watter and run all my hard drives/DVD-R plus all the fans and lights on that power supply, and run just my motherboard and all the things on it with the new power supply, would I risk frying anything? The theory behind this is that if the hard drives are getting power from one power supply, and the signals from it are from another power supply, and there is a differential between them. One power supply would try to charge the other power supply. That is not a good scenerio to have. However if the data signals do not care about that since they are low voltage I would assume, it shouldn't be a big deal right? I planned on having my 2nd PSU on a switch instead of relayed into the first one. This way when I have to do mega rebooting shut downs my hard drives are spared the cycling of power. I also have a crapload of white cathodes in my PC that I use for work lights when I want to mess with something or change out a card. Its pretty handy to be able to leave the 2nd power supply on to do that with the first one turned off on the back.

So, to sum it all up, is this safe? Will it work without harming anything? I plan to find out Monday but I'd like a heads up first if someone here has any ideas about it. Thanks in advance guys.

Jigga
 
However I am not able to give you a definite answer to your question. I would think that it would work. How do you plan on getting the 2nd PSU to start up? And #2 how do you have 9 PSU's in your case :eek: :p.
 
You could always splice the "motherboard on" wire on your main PSU and run a wire to the other one so it would start up at the same time as the computer.
 
I already have 2 PSU's in my case, I use a switch to trigger the second one to turn on. However it just controls the fans and lights. Since its all watercooled I can actually turn all the fans off for a completely silent system except for the 600 watt PSU. I don't do it very often but it is cool to not hear the PC running at all for a few minutes. It does heat up and I have to have the water pump on the main PSU so it atleast moves the water around. Here is a picture of said case.
storagesidenewpaint14my.jpg


Keep in mind I did not have 9 hard drives in it at the time I took the picture. I am getting a raid at work for my work machine which nobody really knows anything about so I may bring that to quakecon with me. 4 more 300GB drives which I can attatch to my 120mm fans on the other side. Here is a picture of the brackets for the 120mm fans.

120fanhdbuv0.jpg

With that I can hold 3 more drives on the other side. So I'd actually have 12 drives as I already have 8. 12 is actually perfect though since the case holds 9 by default. With 2 PSU's, both high quality 600 watt and 700 watt OCZ's I should have more then enough power. Not sure quakecon's power will be able to keep up but I can hope :) I just want to make sure that the 2 PSU's wont fight each other. I read tying the ground of each one psu together should help but I don't want to do that without more info.
 
daphatgrant said:
However I am not able to give you a definite answer to your question. I would think that it would work. How do you plan on getting the 2nd PSU to start up? And #2 how do you have 9 PSU's in your case :eek: :p.
Click to expand...

The U2-UFO is the size of two cases combined, and if you read his sig, I'm not surprised he needs that many. That's a lot of "junk" as he put it.
 
Sorry, I changed it, it was 9 hard drives, not power supplies. If I had that many PSU's I wouldn't have room for any hard drives!
 
Sence you seem to have so much "junk" in your PC why don't you send some of it my way? I'm sure I could find a use for it all. ;) And it would ease the load on your PSU! :D


-Proxy
 
I'm going for the Holy shit factor at quakecon this year. 12 hard drives will grab some attention, especially if they are all mounted internally :) If I sent some junk your way I'd have to go get some more, so not much point in that! Seriously though, does anyone see a problem with my plan?
 
Jiggaman2576 said:
I'm going for the Holy shit factor at quakecon this year. 12 hard drives will grab some attention, especially if they are all mounted internally :) If I sent some junk your way I'd have to go get some more, so not much point in that! Seriously though, does anyone see a problem with my plan?
Click to expand...


Ok, I dont see and problems at all, I have seen many PC's with dual PSU's ( http://www.mypcmadness.com/gallery2/gallery2/main.php?g2_itemId=1114 ) and one with three even. I can't help but, wonder why you don't just get a PC Power&Cool 1KWatt PSU to take the load for both. They are rated for Quad Xeon servers so it's not like you will be loading them down all the way, and it should fit inside that case.


-Proxy
 
Mainly the $500 price tag. I have 1300 watts of power between both of the PSU's I'm using and it will have cost me $320. Pluse like I said, I like to be able to leave the lights on when I'm working on stuff inside. Should I connect a ground from each PSU to give them the same ground point? Wouldn't the screws in teh case do the same thing or do they not have a ground like that.
 
Well, sence you are gonna do two, jump the second PSU, hook the second PSU up to the HDD's and lights, put the primary PSU on the computer itself (i.e. Motherboard/video cards and CD/DVD drives.) Just make shure you power on the HDD PSU first to let them spin up, then power on the PC itself. When you go to shut down, reverse the prosess. Power down the HDD's then the PC. I beleav to jump an ATX PSU it's pin 2 and pin 16 on the M/B connector, might want to check on it though.


-Proxy
 
I already know how to do all that, my main concern is having 2 different power sources hooked to a hard drive. The mobo is going to feed the hard drives the voltage from PSU one for the data signals but it will be powered with PSU 2. This could confuse it or cause issues I would think since the voltages do not reference each other. As far as starting the PSU's up and all that, I've got a switch that I just hook to the green and black wire on the ATX connector. I flip the witch, it shorts those two points and powers up. I plan on leaving the hard drive PSU on all the time. Hard drives last a lot longer if they are never shut off, proven fact. I can turn my fans off with my fanbus since it has a full off position. Hmmkay?
 
Umm, hey RyanL, I know you are trying to help but I mentioned in the post right before the one you posted the link to that I already know how to get 2 PSU's running as I currently already have 2 PSU's, I wanted to more or less know about having 2 separate 12V lines and the differential between them causing problems over the data cables such as IDE and sata. So far nobody has answered that question, they have just said yeah, it should work. I'm going to attempt to make both of the psu's I am using the same voltage by measuring the outputs on a molex connector with a meter. I can dial the 600 watt OCZ in to match the 700 watt OCZ. I'm also going to ground the power supplies together so they have a common ground. This should eliminate any differential problems I am talking about. Thanks for the help guys but I think I got it.
 
I think what you are asking is, if having 2 seperate power supplies in one computer would cause voltage problems if one power supply is slightly under/over voltage by a small amount.

If that is what you mean, then remember, even if you don't connect any of the +V wires to the dame device, you're still connecting the grounds together through the case.

Each power supply self-regulates itself to provide +12VDC based on the voltage of the ground for that power supply, which SHOULD be 0, but it can fluctuate.

So, to answer your question, no, there won't be a problem. You are connecting your PSUs up in exactly the same manner as everyone else who has done it.

I know that was confusing, so let me try to assplain it another way.

Lets say PSU is running the +12VDC line at +13VDC because the ground is +1VDC for some reason. Lets say PSU is running normally.

Since both grounds from both PSUs are connected together through the case, then both power supplies will be seeing a +1VDC voltage on the ground wire (as well as all of your devices) and both supplies will adjust to +13VDC for the +12VDC line.

I hope that helps because I think I confused myself a little.
 
I have been running 2 ps's in my system for over a year now...
no problems so far. I ave both hooked into a 1500va ups though. Maybe you should do that for safety too? :)

ROb
 
Jiggaman2576 said:
I already know how to do all that, my main concern is having 2 different power sources hooked to a hard drive. The mobo is going to feed the hard drives the voltage from PSU one for the data signals but it will be powered with PSU 2. This could confuse it or cause issues I would think since the voltages do not reference each other.
Click to expand...

The two PSUs grounds are tied together, so you have a common ground (good). You have two concerns here:

One, if the drives are always powered on and your MOBO is not. In this care, the drive data cable outputs can drive 3.3V or 5V into your MOBO which is not powered. This can be a bad thing, but not always. Datasheets for logic chips have an absolute maximum input rating that specifies inputs cannot be more than +0.7vdc above the power pin voltage or less than -0.7vdc below the power pin voltage. The chip inputs usually have clamp diodes and series resistors to limit the current so damage does not occur. The drive data cable outputs are also current limited.

Second, if the drives are powered from one supply while the MOBO is powered from another supply. With both power supplies turned on there will probably be a small difference between PSU voltages on the two sides. In this case, as long as PSU #1 and #2 +5vdc are within 5% of each other, and PSU #1 and #2 +12vdc are within 5% of each other you should not have a problem. The data interface between the two sides should be designed to deal with this.
 
Now we are getting somewhere. Those are the answers I was looking for. I plan to regulate both PSU's to get them as close to the same voltage output as I can. Do I need to bother hooking the grounds from each PSU together or will the case do that for me? It would make life easier if I didn't have to mess with it. I'm getting more and more hard locks from the video card sucking so much power so I really hope it fixes all these problems. I'll get some pics when its all hooked up and running/or fried whichever happens :)
 
It's best to have redundant grounds. That doesn't mean you have to tie ALL of the black wires together. I would just tie one or 2 of them together. They all connect to the same place inside anyways.
 
Why not build a small serverbox to put all your drives in?

I ran 1cdrw, 1dvdrw, 10 hard drives, 2 controller card, 2 nics, 1 audigy, barton 2500+ oc'd/overvolted to 2.45ghz, a radeon 9800 flashed to pro and overclocked more, 2 120mm fans, 1 80mm fan(deltas) and 2 neon tubes+leds for fan switches, running a 500w antec tru-power. Never a problem, ever, except not enough power connectors for all the drives

I think if you are not having any problems you should be fine.
 
My PC IS my server box also :) I am the server at all our group's lan parties as well as a server for my xbox/home theater. Quakecon has tons of "Stuff" available and I don't want to limit what I can grab while I'm there. Most of the time I end up erasing half of it anyway. Since the UFO case is so big its basically like having my whole PC in there, and then tossing in massive storage and keeping it all very cool. The ultimate case if you ask me, and working on it is a dream as I can fit my whole damn head inside of it if I need to.
 
Jiggaman2576 said:
My PC IS my server box also :) I am the server at all our group's lan parties as well as a server for my xbox/home theater. Quakecon has tons of "Stuff" available and I don't want to limit what I can grab while I'm there. Most of the time I end up erasing half of it anyway. Since the UFO case is so big its basically like having my whole PC in there, and then tossing in massive storage and keeping it all very cool. The ultimate case if you ask me, and working on it is a dream as I can fit my whole damn head inside of it if I need to.
Click to expand...


Even more reason to run dedicated hardware.

After my fiasco with my pc I eventually built a server box, with that many drives in it, it was heavy as hell and a pita to work on the inside. Also, when you get 6+ people pulling files at a lan, and you are hosting the game, there are complaints, but the networks at most of the lans I went to sucked, it was sad when I would go to the trunk of my car and get my switches an all of a sudden the lan party was a lan party.
 
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