Can you use a seperate psu to power a watercooling system?

pastymuncher · 30 Jan 2006 at 11:42

As in the title. If so how do i get it to power up without a motherboard. I know there is a way you can short, presumably, the 20/24 pin plug but is this safe or is there a safer way as this will be permanent.

My watercooling rig will be cooling only my 2x BFG 7800gt's and nothing else. The pump, reservoir, radiator and fans, psu etc will be in a purpose built box bolted to the underside of my desk with a slot cut in the desk top to fit the rad and let it blow its hot air upwards. The reason i am doing this is that at the moment my 2x BFG's are blowing air out the front of the case straight at me and it gets ridiculously hot when they are working hard. On top of that the heat that can't get out of the case is building up in the case and temps are rising. Yes i could get AC heatsinks but i don't trust AC anymore after a Freezer 64 let all its fluid go everywhere inside my case one day. Anyway i don't want to go back to dual slot cooling. Zalman coolers would be just as bad as it is now, if not worse.

The answer, get the heat out via water cooling.

So rather than run a very, very long extension from my psu to the box i want to put it's own small psu in there to power the pump and fans etc. Can it be done?

Many thanks in advance for your replies/advice.

fragster · 30 Jan 2006 at 12:17

I don't see why it can't mate.

I remember people using a paperclip to bridge the two pins so that the PSU came on whenever the switch at the back was on.

Your only worry is that you would have to remember to switch this second PSU on when you turned the computer on.

I also recall OcUK selling a simple relay switch that powered a second PSU when the first was turned on...not sure if they still do it? A single molex plug from each PSU was all that was needed.

Good luck

Martynt74 · 30 Jan 2006 at 12:19

Yeah you'd need to buy or make a relay so that both psu's were activated when you pushed the switch, it'd help incase you ever forgot to switch the extra psu on

pastymuncher · 30 Jan 2006 at 12:28

Thanks for the replies so far guys. It won't be a problem forgetting to turn the extra psu on as it will be plugged into the same antisurge extension as the pc. What i want is for it to run seperately so that i can leave it on after the pc has shut down for 10-15 minutes so it will keep circulating water for a while. Just like some psu's keep the fan running after shutdown. Also this would greatly help with setting up, bleeding the system and the initial 24hrs leak test.

Martynt74 · 30 Jan 2006 at 12:31

Have you bought a pump yet?

If you get an aquarium pump like the eheim 1250 they are designed to be ran 24/7 then if you used 240v fans on the rad it could just all be on an extension cable and just switch it on at the wall and it'd all turn on. No PSU would be needed

MikeTimbers · 30 Jan 2006 at 12:46

Or get an AT PSU off [auction site], which has an actual power switch (gasp)

pastymuncher · 30 Jan 2006 at 14:33

The Eheim 1250 is actually my number 1 choice of pump closely followed by the DD D5. Can you actually get 240v 120mm fans? Will they not be very loud?

OK, thicko time. :confused:

What is the difference between an AT psu and an ATX psu?

MikeTimbers · 30 Jan 2006 at 14:51

The AT PSU had an actual on-off switch that stuck out the front of the case. It had the same Molex connectors for hard disks etc but the motherboard connector was completely different. If all you want is a way of powering standard 12v/5v things like pumps or fans an AT PSU will do the job perfectly and should be really cheap.

240v fans can be got from the holiday camp high-street store (80mm/92mm) but if you want the best you need to look for Comair Rotron AC fans. For a radbox, the benefits are clear. Easy power, with easy power regulation to reduce the noise. Place the fans in the middle of the box with the radiator/heatercores at the edges. Use simple light-switch dimmers for controlling the power/noise.

pastymuncher · 30 Jan 2006 at 15:01

That is excellent and just the info i was looking for. Am i right in thinking then that these AT psu's were of the old type when the operating system told you it was ok to turn off your pc? If so sounds just what i need then. Is a Eheim 1250 240v mains with a standard 3 pin plug? I looked on their website and everybodys that sells them but it does'nt actually say. The DD D5 which is 12v is either out of stock or ridiculously overpriced at the ones who do have it so it looks like the Eheim anyway.

weescott · 30 Jan 2006 at 16:11

I use a separate PSU for my pump / fans / and optical drives. I use the highly complicated paperclip mod so the PSU switches on without being connected to a motherboard!

KiNgPiN83 · 30 Jan 2006 at 17:38

I was contemplating a secondary PSU but in the end i went for a relay, mainly because it took up a lot less room than another PSU. The relay i bought was the, Criticool PowerPlant II Pump Relay Card. Works excellently and also has a switch so you can turn it on without the PC for leak testing etc.

pastymuncher · 30 Jan 2006 at 20:12

Cheers guys, thanks for the replies especially MikeTimbers for hitting the nail bang on the head. Secondary AT psu it is then.

MikeTimbers · 30 Jan 2006 at 21:53

pastymuncher said:
That is excellent and just the info i was looking for. Am i right in thinking then that these AT psu's were of the old type when the operating system told you it was ok to turn off your pc?

Yes.

pastymuncher said:
Is a Eheim 1250 240v mains with a standard 3 pin plug? I looked on their website and everybodys that sells them but it does'nt actually say. The DD D5 which is 12v is either out of stock or ridiculously overpriced at the ones who do have it so it looks like the Eheim anyway.

Eheim1250 will come with a standard 3-cable lead with either a European 2 pin or a UK 3-pin. Make sure you leave on the original 5/8" inlet as the extra girth permits much greater outlet flowrate and pressure.

Good luck and post pictures when you're done.

VaderDSL · 30 Jan 2006 at 22:03

pastymuncher said:
The Eheim 1250 is actually my number 1 choice of pump closely followed by the DD D5. Can you actually get 240v 120mm fans? Will they not be very loud?

OK, thicko time. What is the difference between an AT psu and an ATX psu?

you can indeed get 240/230V fans

I have two steel papsts, huge 38mm thick beasts (might be even thicker)

I wired them up to a voltage selector mains adaptor (the ones you tend to get for electronic keyboards (the musical kind) I had the choice of 12V, 9V, 7.5V, 5V 4V

I used to run them at 7.5V they were quiet, sort of a low swish sound and still moved a good amount of air with a shroud