Suitable wattage for secondary Psu

Ok, I'm expanding the loop again and have need of a secondary Psu to power some bits I want powered separately from the main rig,
it will run separately from the main Psu so that one can concentrate on feeding a 4.6GHz 975be and two 6950DCIIH20's
The two Psu's will not be connected in any way shape or form, at all
I'm tempted to grab a Cx600w just to cover things but thought I'd ask a few folks on here what they thought would be a suitable rating,
Psu2 will power;

Three Xspc X20 750l pumps
two Nesteq 8 channels fan controllers feeding fourteen fans
One chiller box (48W peltier plate, about 4A draw if I'm right)
Xspc temp sensor/display (negligible draw)
So, what do you reckon? 400W, 600W, another TX850?
I figure I'm going to get some questions so....

The Secondary Psu will have a switch in the radbox to turn it on, this lets me run the loop without having the Pc on, so flushing is still a walkaway process or just keeping the water moving in cold weather so it doesn't freeze doesn't require me to have the Pc running, saving my electric bill :P
It also allows cooling the Chip after the Pc is turned off, minor point but a nice touch
The chiller will also have a switch in there so I can turn the peltier on or off as I wish, as well as a temp sensor for the chiller (probably mounting that on the chiller itself)
fan controllers let me turn the fans off so even if the pumps are running they don't have to be
and I won't forget to turn the pumps on when I switch the Pc on, due to the design of my radbox, my Firefly obsession and my Ocd, it can't happen, and even if it ever did, my sensors will tell me that my temps are shooting up, reminding me :)
6 answers Last reply Best Answer
More about suitable wattage secondary
  1. 400~450W gold rated PSU, just off the top of my head calc though. Will take a look in the morning(or when my brain has cooled down)

  2. I was thinking/looking at maybe the Cx 500, my brains melty today too, and I'm at work now :-p
  3. Best answer
    Would be looking at something like a 300W unit, cant imagine those components drawing more than ~160W at most.
    From what I remember of researching my water loop with that pump, its draw was something low like 12W. Fans would draw 10W at absolute most, would think much less. So roughly 110W between the fans and pumps. Plus a 48W Peltier and that's roughly 160W being drawn.

    So with a 300W unit your going to be running at ~50% load with everything maxed, which is a bit lower than a PSU typical peak efficiency (roughly 70%), but isnt too bad. With the fans turned down, your usage may get closer to 30%.
    Better than getting a higher wattage unit, as 80+ Certification only covers loads between 20 and 100%, once it drops below that, your efficiency and voltage control isn't guaranteed.

    Only unit of repute I could find thats 300W is this.

    Though this might be one of the rare few situations where the 5v and 3.3v rails will be more important than the 12v. Both those rails on the above PSU provide a total of... 150W. Might want to see if theres anyway to convert a 24pin ATX or 4pin CPU power into a Molex connectors, otherwise you mat run out of watts on the 3.3 and 5v rails while the 12v is sitting pretty on its 408W.
  4. I'm not sure how/why the 5v or 3.3v would be involved, I'd plug everything onto the molex lines, you could be right about stealing the 12v from the 20+4 pin,
    dedicated amps for the peltier would be nice
    Maybe a Cx430 then, I'll check it out and thanks for the input MoC :)
    **Edit, Yup, JG likes it well enough, I reckon we have a winner then :)
  5. Ended up buying the Cx500 in the end, couple of quid more, so daft not to :)
    Should be here monday hopefully
  6. Best answer selected by Motopsychojdn.
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