Personal computing discussed

Moderators: SpotTheCat, Nemesis

Grand Gerbil Poohbah
Topic Author
Posts: 3396
Joined: Thu Nov 04, 2004 5:45 pm
Location: Alaska

PSU w/4 x 12v Rails

Sat Feb 25, 2012 10:48 am

I don't forsee this being an issue, but its been a long time since the multiple 12v rails have been a hit. I recall the more rails (as long as they were decent amps), the better.

Anyhow, I've got an Etasis 750w PSU with 4 x 12v rails at 18a per rail. Planning on using this for the P67 Sabertooth, I5-2500k, 2 x 8gig Corsair Vengeance 1600 system that I just purchased last night. ... dsli_psu/7

I bought this thing about 2 years ago in anticipation of a new computer build. I got it for a screaming deal at the time of 49.99 (not counting shipping to Alaska unfortunately). I realize its based on an older design, but everything appears to be pretty rock solid with this PSU from the looks of reviews on it. I just recently pulled it out of the box for the first time since I purchased it and confirmed it on a spare system, boots it up fine and ran the system for a little over a day.

My plan is to make sure that I plug the auxiliary 6pin PCI-E connectors into GPU from the different 12v rails to spread the power out to different rails, which should make it run pretty stable. If I dedicated 2 of those rails to the video card alone, I should be golden. That leaves the other 2 rails for use with other components like drives and fans, ect. Any flaws in that logic?

The video card I'm considering slapping in this rig is a 6950 which was stated as needing a 12v rail with an amperage of 30 total. Since these are 18a rails, 2 of them would be 36, keeping me safely within that requirement.
"I think there is a world market for maybe five computers."
Thomas Watson, chairman of IBM, 1943

R5 1600x|ROG Strix B350-F|CM 240 Lite|16GB G.Skill 3200|MSI 7850 2GB|500gb 850 EVO|Corsair 400R|Seasonic X Series 850w Gold|Corsair M95 / K90
Gerbil XP
Posts: 359
Joined: Fri Dec 12, 2008 3:42 pm

Re: PSU w/4 x 12v Rails

Sat Feb 25, 2012 11:29 am

Yeah that is the theory. :wink:

Just make sure you know what rail goes to the CPU,(also 12V) and have two independent rails going to the card and you should not have a problem.

The difficulty occurs when the PCIE rail is shared with the CPU. (Usually with older and poorly designed {cheap} PSU)

PS The AMD 6950 will never need that much wattage...They always require much more than they need for the recommendation :wink: .
Gerbil Jedi
Posts: 1899
Joined: Fri Aug 20, 2010 6:03 pm
Location: philly suburbs

Re: PSU w/4 x 12v Rails

Tue Feb 28, 2012 6:44 am

Well looking at your PSU your EPS12v (8-pin) cable gives your cpu its 12 volt juice.Now to figure out what PCIe power connector shares that same 12volt rail.A schematic would be nice.I wonder if you can use a volt/ohm meter on the PSU powered off on the 8pin cpu 12 volt output wire,then while its connected to that use your other ohm lead and probe each of the 12v output wires from the 4 blue PCIe connectors.Once you get a ohm reading besides infinity/open you will know what PCIe connector not to use on your video card.Or you could jump the power supply so it runs,then measure the voltage from the same wires i said before and use a common ground.perhaps the 8 pin cpu connector and the PCIe connector with identical or closest to identical voltage would share the same is a link that might be helpful.
I googled how many amps a 2500k uses and came up with nothing but a forum post saying a 2500k uses 6 more amps at 4.9ghz volts then at stock freq.
Good luck too bad your in alaska,we could have figured it out together or made some smoke or smoked and then figured it out.I like that kinda stuff,hate doing it on cars since i have been doing it for 25 years.But on a hobby its fun. :evil: see i need some eye drops,ocuclear or visine.
Now i know it says it supports a dual core,but you have a Q core and even though its built on a smaller node it seems like they put out more heat then older duals and singles minus the prescott.I am currently pumping 1.68 volts into a old 940 pin fx53 2.4 ctock now at 2665 mhz with just a 4800x2 stock amd heatpipe heatsink and i wont go over 55c loaded,idles High 30s.It just seems the new cpus pull more power at the socket.Just a hypothesis of mine.With the increased cores,freq possibly leakage,plus more and more of the motherboards functions are now on the cpu.I dunno i could be totally wrong.But i sounds correct to me.
2600k@4848mhz @1.4v CM Nepton40XL 16gb Ram 2x EVGA GTX770 4gb Classified cards in SLI@1280mhz Stock boost on a GAP67-UD4-B3, SBlaster Z powered by TX-850 PSU pushing a 34" LG 21/9 3440-1440 IPS panel. Pieced together 2.1 sound system

Who is online

Users browsing this forum: No registered users and 2 guests