Add2PSU (psu combiner thing)?

If you want to do load-sharing across multiple PSUs, the PSUs need to have almost perfectly identical voltage outputs or otherwise whichever PSU has the highest output on any given rail will end up feeding the loads until either wire resistance brings it low enough for other PSUs to start providing power or a single PSU's rail ends up tripping over-current protections.

Another potential danger from crude load-sharing is that if over-voltage protections get tripped on one PSU, the crowbar circuitry will need to short the combined output of all PSUs which could very well destroy it and cause a nasty inductive spike on rails.

Real load-sharing PSUs share their reference/control voltages and fault protections so they can react in unison instead of potentially destroying each other and your equipment.

Wouldnt touch that thing with a 10 foot pole.

Why do you need to add a second PSU if you already have a 620 W PSU? Two 620W units are going to cost you more than a single good 850 W unit which will be more than enough to handle pretty much any system.

I refer your attention to this post on overclock.net by phaedrus,
http://www.overclock.net/t/1177714/faq-dual-power-suppl...

He is well versed in power supplies, and I agree with his assessment, so the first question you need to ask yourself is why do you feel the need to use two?

Well, Im thinking about SLi 670s or something of the sorts and buy a water cooler around christmas this year, and i dont think that 620w will be enough. and im only 15 so im dead broke and was looking for a cheap alternative. but thank you for the output. and since i already have the 400w i thought it might work. ill just sell it now, however.

i found this http://www.newegg.com/Product/Product.aspx?Item=N82E168...
on a different forum involving the cable i mentioned, but i dont know what it is... could someone explain it to me? thanks in advance.

EDIT: my 620w is a Antec Neo ECO 620c

Those booster PSUs provide additional 12 V power in the form of PCI-e connectors, those feed the graphics cards directly, it is a much simpler and safer option than combining two full ATX PSUs.

On the upside, nvidia managed to tone down their power consumption figures quite a bit so two GTX 670s are actually capable of running on a 620 W PSU since they only pull 170 W per card at full load, guru 3d had a system with 2 GTX 670s in SLI only pulling 433 W from the wall which leaves plenty for the rest of a system.
http://www.guru3d.com/article/geforce-gtx-670-2-and-3wa...

Also, if you are only 15 and limited on money, i would skip on the water cooling for a while, the self contained water coolers like the H50 from corsair are significantly more expensive than a similarly performing air cooler, and a full blown water cooling system will cost a few hundred dollars so you might want to just focus on performance components until you have some cash to spare.

Interesting gadget.

This is a 120/240V to 12VDC-only 450W PSU with 2x 6-pin PCIe + 2x 8-pin PCIe connectors. This thing should be a reasonable option for people who want to supplement their main PSU instead of replacing it. I would still be a little worried about orderly power-up/shutdown between the two PSUs.

620 is plenty for that. Especially with a quality PSU, if you need more power, buy a new PSU dont use that garbage you linked. Seriously, could end up costing you another system in costs.

as in garbage, do you mean the add2psu thing, or the psu supplement? im very new to computer and the other two said the supplement should be alright, but another opinion cant hurt.

@hunter315 i didnt know that it drew that little. im really new to computers but i did build mine so i guess im a novice, but thought they took in much more power.

All of the nvidia cards in the x70 range leading up to the 670 used to suck down power like no tomorrow, the GTX 570 has a TDP of 219 W, the GTX 470 was 215 W, and the GTX 275 was 219 W, so a pair of 670s in SLI does use considerably less power than a pair of 570s, Guru3d had a 570 SLI system sucking down 578 W(145W more) from the wall which would not work on your 620 W PSU, so it is understandable that you expected it to take a ton more power, a lot of the more recent cards did.
http://www.guru3d.com/article/geforce-gtx-570-sli-revie...

Best answer selected by illegalrugalah.

ok, awesome. if i need to upgrade my psu ever ill probably buy one of those.
i have an amd cpu so its not as power efficient, and i dont have the money to buy a intel mobo AND a high quality cpu

thanks everyone 

Just as with the Add2psu chip, the molex connector sends a signal to a relay in the booster pack to turn it on
Other than the fact that it only provides 12v pcie power, the boosterpack is the same as adding a secondary psu

interesting. thanks