[r0frog]

Well, I'm going SLi in about a week. Dual 6600GTs. (Yeah yeah, but hey. I get 10k 3D03 with just one..) but I don't think my PSU is up to the task. (480W, 12v=17a)

Now, I'm looking into a 420W, with 2 12v rails, both at 18A. Now it says this equals 29A, but does it actually? As in, my 66GTs don't have anything to plug into, for extra 12v powering, so is it going to just be the same as 18A?

I'm crap at asking questions.

[Careface]

as far as i know, the 2 rails are seperate and dont combine into one 12V rail with a massive amount of amps.. if im not much mistaken, arent dual 12V rails meant for things that need a dedicated rail? as in, a high powered GFX card that needed an extra molex cable. youd plug one of the 12V rails into there, so then the other 12V rail wouldnt be saturated by the video card?.. correct me if im wrong though, ive never owned a dual 12v psu

Careface*

[D17S]

Been doing a little power supply research for an SLI project too. I've found the 12v rails are completely separate on these dual rail power supplies. There seems to be some slight variations though.

Antec says their 12v1 powers the CPU and motherboard components - like a Vcard's power though the AGP socket. In this case, 12V1 would be powering your CPU and would also be the only source for your SLI'd Vcards (as you describe there are no additional plugs with these.) In this case, your concern seems well founded.

Enermax says 12v1 is dedicated to the CPU alone. That leaves 12v2 for motherboard components (like a Vcard's power though the AGP socket) and drives, peripherals and everything else. In this case, your concern seems still well founded.

Also, you noticed the numbers don’t add up too well. I added up the advertised ANTEC numbers from those charts. Antec’s 18 amp/12v rails and the XXamp/5v, etal. I got 780 watts available watts from a 550 watt PS. So I asked. They went on and on about this and that. Did I just not get it, or was there just nothing to get? (. . . probably a bit of both). One thing for sure though. The dual 12v rails are isolated. One rail doesn’t share excess capacity with the other. It seemed to me, that even with the biggest dogs, I would be buying a shared 20 amp, 12v rail'd PS for my Vcards. That’s not enough for me.

I decided to forgo the dual rail PSs and go with a strong 12v single rail (Still shopping). I decided the best bet was to get something that can keep the well filled, then just let everybody stick in a straw and take what they need. That way, I don’t have to worry about anyone coming up a bit thirsty.