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How can I hook up 2 PSUs to the same PC?

R

rcomo

Senior member
I would like to have all my components (opticals, HDs) on one PSU and all my mods (lights, fans, etc) on another PSU. However, the only thing I know that will turn on the PSU is the motherboard on switch, that I only know that 1 hook up will work. Can I somehow mod the switch at my front panel to turn on both PSUs at the same time?
 
If you look at an ATX power connector you will see a green and blue wire with a black one in between on one side of the connector. To turn on an ATX power supply you need to short that black wire and the green one. Simply sticking a paper clip in them will do the trick.
 
Originally posted by: Pariah
If you look at an ATX power connector you will see a green and blue wire with a black one in between on one side of the connector. To turn on an ATX power supply you need to short that black wire and the green one. Simply sticking a paper clip in them will do the trick.
Click to expand...

So follow up question: does that mean that the 2nd psu will alawys be on? Is there a way to hook it up so my front panel switch will turn both PSUs on at the same time?
 
I have to ask....why?

Sure you can mod a power switch to turn on 2 PSUs but is it really worth it? What's in this box that you'll need 2 PSUs?
 
Originally posted by: mikecel79
I have to ask....why?

Sure you can mod a power switch to turn on 2 PSUs but is it really worth it? What's in this box that you'll need 2 PSUs?
Click to expand...

Because I can't get the system to post with everything hooked up all at once, but if I take out my fans/lights then no problem on posting. I am assuming my 1 PSU is not powerful enough for what I want to do, and I have an extra PSU that I can use. I dont want to buy a new one, because I figuire in 1+ years with PCI express and nVidia with their new vid card connection, everyone will need to upgrade then, why spend $$ on a PSU now when you will have to buy one later. This is the easiest solution I can think of, unless maybe you have one better (hopefully! I will take all suggestions).

OH and Mike ~ is there something I should know about putting 2 PSUs together that could potentially be very bad? your question makes me think that maybe there is a drawback to doing this?
 
you'd have to attach the green and black wires of the other power supply to the green and black wires leading from the mobo jumper to the power switch. You can solder an extension wire or just twist them around each other.
 
Originally posted by: rcomo
Because I can't get the system to post with everything hooked up all at once, but if I take out my fans/lights then no problem on posting. I am assuming my 1 PSU is not powerful enough for what I want to do, and I have an extra PSU that I can use. I dont want to buy a new one, because I figuire in 1+ years with PCI express and nVidia with their new vid card connection, everyone will need to upgrade then, why spend $$ on a PSU now when you will have to buy one later. This is the easiest solution I can think of, unless maybe you have one better (hopefully! I will take all suggestions).

OH and Mike ~ is there something I should know about putting 2 PSUs together that could potentially be very bad? your question makes me think that maybe there is a drawback to doing this?
Click to expand...

There's nothing bad about it. Just seems like a lot of work. What kind of PSU are you using now?

BTW nVidia's new video card connection was for laptops, not for desktops. Desktops will use a 16x PCI-E connection.

Also I don't think that BTX will have a new connector for PSUs. I'm pretty sure that there was talk of ATX PSUs being compatible with BTX boards.
 
Originally posted by: mikecel79
Originally posted by: rcomo
Because I can't get the system to post with everything hooked up all at once, but if I take out my fans/lights then no problem on posting. I am assuming my 1 PSU is not powerful enough for what I want to do, and I have an extra PSU that I can use. I dont want to buy a new one, because I figuire in 1+ years with PCI express and nVidia with their new vid card connection, everyone will need to upgrade then, why spend $$ on a PSU now when you will have to buy one later. This is the easiest solution I can think of, unless maybe you have one better (hopefully! I will take all suggestions).

OH and Mike ~ is there something I should know about putting 2 PSUs together that could potentially be very bad? your question makes me think that maybe there is a drawback to doing this?
Click to expand...

There's nothing bad about it. Just seems like a lot of work. What kind of PSU are you using now?

BTW nVidia's new video card connection was for laptops, not for desktops. Desktops will use a 16x PCI-E connection.

Also I don't think that BTX will have a new connector for PSUs. I'm pretty sure that there was talk of ATX PSUs being compatible with BTX boards.
Click to expand...

But from the PCI-Express 6800's there was a new power connector (as seen on Anandtech's main page), plus there will be more avaiilability of SATA drives, which is probably what the OP will get in future upgrades.
Both these will involve new PUS connections, and since he already has a spare PSU, why not make use of it rather thna buying an expensive new one?
 
Originally posted by: mikecel79

There's nothing bad about it. Just seems like a lot of work. What kind of PSU are you using now?

BTW nVidia's new video card connection was for laptops, not for desktops. Desktops will use a 16x PCI-E connection.

Also I don't think that BTX will have a new connector for PSUs. I'm pretty sure that there was talk of ATX PSUs being compatible with BTX boards.
Click to expand...


Currently, I have a 480w Thermaltake. I have 2 opticals, 2 HDs, 4 fans (92mm x2, 80mm x2), 4 cold cathode bulbs, 9800pro, Audigy 2zs, Abit AI7, 56k, Zalman 7000Cu. When everything is plugged in - no deal. When I unplug everything - except for the neccessary stuff - I can post. Since I have an extra 420W PSU, I thought that would be the easiest, CHEAPEST solution. Any suggestions? I really don't mind modding, I actually like it.
 
I would look for a short in a fan or one of the cold cathodes. 480w is more than enough power for that.

For example at work we have a file server with 2 redundant power supplies of 500w each. This server is dual 1Ghz Xeons, 3GB RAM, and 12 10k RPM SCSI drives, SCSI RAID controller, CD-ROM, 12 fans, and 3 NICs. The server is designed to run on just a single 500w power supply. If that server can get by with 500w then you machine should be able to get by with 480w.
 
...but I'm sure that server of yours stagger-spins the 12 drives. All of that stuff can draw double its normal power when you first turn on the machine.

Still, there's a good chance there's a problem with his PS or other hardware. It'd be good to test everything and see if something needs replaced before you begin modding power switches.
 
It can easily be done, but your reason for doing so if faulty, in my opinion. With a power supply that good and rated at that output, something must be rong elsewhere in your system. You should not be having loading problems. Double check everything else in your setup carefully. Otherwise you might lose that excellent power supply too early in its useful product life. And you might damage other components.

But, I assume you are determined to do this. So go to a good electrical supply house... not Radio Shack or Lafayette. Get highest quality switch components with superior grade of wire. Solder rather than twist, then cap. Then tape and strap.
 
Originally posted by: rcomo
Currently, I have a 480w Thermaltake. I have 2 opticals, 2 HDs, 4 fans (92mm x2, 80mm x2), 4 cold cathode bulbs, 9800pro, Audigy 2zs, Abit AI7, 56k, Zalman 7000Cu. When everything is plugged in - no deal. When I unplug everything - except for the neccessary stuff - I can post. Since I have an extra 420W PSU, I thought that would be the easiest, CHEAPEST solution. Any suggestions? I really don't mind modding, I actually like it.
Click to expand...

That's an interesting datapoint. A friend of mine recently upgraded, and got a ThermalTake case, with I think the same PSU. The case includes like 7 fans or something crazy in it, he added a cold-cathode bulb, and is running some Athlon 2500+, Abit NF2 "Deluxe" mobo with all the trimmings, like 2-3 HDs, 2 opticals, fan-speed controller (came with case, I think), not sure what else he has in there, I think an Audigy and a Promise Ultra133 TX2, MSI AGP GF4 Ti4200 with VIVO features, not many other cards.

Anyways, he had to disable the CC light and some of the fans, to be able to reliably power-on and post.

That's something that I couldn't quite understand either - one would think that a "480W" PSU would probably be able to handle those things.
 
VirtualLarry it also depends ont he 'quality' of that 480W PSU, and not just it's rating.

Koing
 
Originally posted by: Koing
VirtualLarry it also depends ont he 'quality' of that 480W PSU, and not just it's rating.

Koing
Click to expand...
This particular TT 480w has been well-rated by many review sites including AT's as being quite stable and conservative in its ratings. 😉

i'd try another PS and/or put components back together one at a time to see if there isn't another problem.
 
Originally posted by: Lonyo

But from the PCI-Express 6800's there was a new power connector (as seen on Anandtech's main page), plus there will be more avaiilability of SATA drives, which is probably what the OP will get in future upgrades.
Both these will involve new PUS connections, and since he already has a spare PSU, why not make use of it rather thna buying an expensive new one?
Click to expand...

That new connector isn't a big issue. NVidia is including an adaptor that lets you plug it up to a standard 4-pin Molex, just like the SATA power adapters let you, so as long as you get an appropriately heft power supply that can handle a decent load you should be fine no matter what new connector they dream up.
 
Originally posted by: dakels
Never had a problem ever. I put bus powered firewire devices on it too with no problem. I dont have any cathode lights though. How much power do those light take? Peak startup power and on what power rail
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Well, the CC light is what seems to put the power draw over the edge, so I definately suspect that something is not right with that component. It draws from the 12v line, I'm pretty sure, along with the 7 other case fans.

Edit: Oh yeah, now I remember. He can run all of those things, he just has to turn the CC light off to boot, then after the system is booted, he can turn it on (still connected all the time, I guess).
Maybe some other component has a very high inrush/startup current rating.
 
I have the CC light off at power up and it has the same problem at boot. Also, the front of my case (the lights on the door that show HD activity) don't work either, they did before I switched PSUs. How would I check to see if somehting is shorting out somewhere? I am all ready to do this dual PSU thing, but would (abviously) much rather get my thermaltake to power everything, as adding a mod is something that is "fun" but alot of extra work.
 
This might sound really silly, but have you tryed putting ( within BIOS ) a delay on your hard drives spinning up ? Is should be called 'boot delay' or something like that maybe under power options in bios, or maybe under advanced i know i can do it, and set each hard drive to delay say the 1st, 3 seconds, the 2nd 6 seconds and the 3rd drive 9 seconds, thus your PSU does not get one huge burst of effort when booting as each drive spinns up at a specified interval, hope this helps.
 
Well the mobo i got is just some stoopid lil Via thing, had it about 8 months or so and that has the delay option. Hope you get it sorted 🙂
 
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