Sign in with
Sign up | Sign in
Your question

Connecting GPU to PSU > 2 separate 12V rails.

Last response: in Graphics & Displays
Share
October 25, 2011 9:28:43 PM

Recently i upgraded to a GTX570. Windows was locking up and freezing. I have exhausted almost all possible causes.

Here comes the noobish part >

Apparently I should be running the 1 x 6pin and 1 x 8 pin on seperate 12v rails.

tbh I just connected a adaptor (http://www.maplin.co.uk/pci-express-power-converter-468...) to two unspecific LP4 connectors. This gave me 3 x6 pin PCI power connections. And then i used a 2 x 6pin to 8 pin adaptor ( http://www.apitcomp.ru/catalog/adapters/131501.jpg ) to give me 1 x 6 & 1 x 8 pin.
Diagram > http://i.imgur.com/IJRja.jpg

in hindsight this was probably a mistake. can i get some advice on which rails i should be using and how to connect my GPU correctly.

EDIT: I have supplied a picture of my power supply http://i.imgur.com/Yf4yb.jpg clearly this information printed n the side is referring to the rails. however how do i know which ones to plug the GPU into?

EDIT: Here are my connectors and I have labelled them for ease > http://i.imgur.com/Am5fh.jpg
a c 376 U Graphics card
October 25, 2011 9:52:44 PM

I doubt it is a problem with balancing. Your card is receiving power from 6 different connectors apparently, the 4 molex connectors, the 6-pin and the PCI-E slot itself. If all of those are the same rail there's something terribly wrong with how the PSU was designed. Furthermore the 24a you have available on each rail(supposedly) is equal to 288w while the GTX 570 uses about 200w under normal usage.
It could still be a problem with the PSU, just not the one you are talking about. Either it or the card could be faulty.
a b U Graphics card
October 25, 2011 10:27:50 PM

a solid 750w PSU should have 60a+ on the 12v rail. your PSU is probably in the 40a ballpark (can't tell with the lack of info in the pic, also not a good sign). the fact that PSU lacks PCI-E connectors is another bad sign. since you upgraded your video card, an upgrade to a quality PSU would also be a wise investment.

FYI, your PSU has a single 12v rail that has split. Most PSU that actually have two 12v rails tend to be 1000w+. For example my PSU has 12v1-12v4 but it's just a 4x split off of one 12v rail.
Related resources
October 25, 2011 10:51:19 PM

Can you recommend a good quality PSU for this card?
a b U Graphics card
October 25, 2011 10:55:28 PM

what is your budget and what web site do you shop on

some budget models would be

corsair CX600 v2
antec neo eco 620
antec earth watt 650
OCZ modstream 600w
OCZ Stealthstream 2 600w
a c 259 U Graphics card
October 25, 2011 11:18:51 PM

Good comments from previous posters.

The two 24a rails your psu has is probably an artificial limit which restricts outputs to 24a to satisfy ul safety requirements. If you rearrange the connectors, you might do better. Your psu is suspect, even though the advertised watts are ok. It looks like a cheap older design, and I would not trust it much.

EVGA says that a GTX570 needs 550w with 38a on the 12v rails plus two 6-pin PCI-E power leads.
a GTX580 needs 600w with 42a on the 12v rails plus one 6-pin and one 8-pin PCI-E power lead.

You must have a special GTX570 that needs power more like a GTX580.

Whatever you do, get a quality psu. Cheap units do not deliver advertised power under load or at higher temperatures.

My short list of quality brands includes Seasonic, PC P&C, Corsair, Antec and XFX.

If you get a 650w unit from any of them, you should be ok.
It is not wrong to overprovision a bit, say to 750w.
a b U Graphics card
October 25, 2011 11:20:58 PM

billj214 said:
You will need a power supply with at least 42amps on the 12v rail.

I recommend Corsair TX650 or larger. (52a on 12v)

http://www.newegg.com/Product/Product.aspx?Item=N82E168...


you make that figure off the top of your head and try to pass it off as fact?

while the corsair TX650 is a very good unit, he certainly does not need it nor have at least 42a since the official Nvidia requirement is

Minimum 550W or greater system power supply (with a minimum 12V current rating of 38A)


October 25, 2011 11:50:07 PM

dirtyferret said:
you make that figure off the top of your head and try to pass it off as fact?

while the corsair TX650 is a very good unit, he certainly does not need it nor have at least 42a since the official Nvidia requirement is

Minimum 550W or greater system power supply (with a minimum 12V current rating of 38A)



So 550 watts means nothing without knowing the 12v rail amperage and yes the requirement for GTX570 is 38a but 42a gives a little more headroom.
Also nothing in this forum can be treated as fact, the only fact is that nobody knows everything! Except you of course!
a b U Graphics card
October 25, 2011 11:55:21 PM

billj214 said:
So 550 watts means nothing without knowing the 12v rail amperage and yes the requirement for GTX570 is 38a but 42a gives a little more headroom.
Also nothing in this forum can be treated as fact, the only fact is that nobody knows everything! Except you of course!


...it gives the amps next to the the 550w...its the the "38a" :pfff: 

some things can be treated as fact like the fact that Nvidia recommends "Minimum 550W or greater system power supply (with a minimum 12V current rating of 38A". you see that is a fact, they do indeed recommend it. :pfff: 

while 42a is more headroom i reiterate it is not a "need" :pfff: 
a c 194 U Graphics card
October 26, 2011 12:07:50 AM

Its generally helpful to know how power supply recommendations that nVidia and AMD list are created. They use a hefty system with a high end CPU and many drives to attempt to give a worst case scenario and alot for POS PSUs. The number they list is excessive intentionally so that if you have what they list it will run fine.


Lets do some power math shall we? A GTX 570 has a TDP of about 220 W, round up to 250 W to give some fudge room, add in a 150 W CPU, 50 W for everything else, and you are still only at 450 W so a good little 500 W unit is plenty to run the system even with some overclocking and thats with fluffy math to give overhead, you certainly dont need a 650 W unit. The Corsair 550 TXM is out now and it has plenty of power for that setup, its $80 after $10 MIR and 10% off promo code right now.
http://www.newegg.com/Product/Product.aspx?Item=N82E168...
October 26, 2011 12:55:32 AM

I still stand by my recommendation of 650w or better, I own a GTX 580 which after running on a Corsair TX650 the PSU gets very hot.
My Corsair TX850 runs about half as hot which after several hours of sustained 100% GPU and CPU usage playing Crysis2 or BF2 .
So my recommendation is based on real world experience and the fact that anything less than a 650w PSU will most likely run hot.
a c 171 U Graphics card
October 26, 2011 1:30:52 AM

dirtyferret said:
a solid 750w PSU should have 60a+ on the 12v rail. your PSU is probably in the 40a ballpark (can't tell with the lack of info in the pic, also not a good sign). the fact that PSU lacks PCI-E connectors is another bad sign. since you upgraded your video card, an upgrade to a quality PSU would also be a wise investment.

this is absolutely correct, your psu is no good to run a gtx570 from, it will fail. get a decent psu.
a b U Graphics card
October 26, 2011 1:50:14 AM

billj214 said:
I still stand by my recommendation of 650w or better, I own a GTX 580 which after running on a Corsair TX650 the PSU gets very hot.
My Corsair TX850 runs about half as hot which after several hours of sustained 100% GPU and CPU usage playing Crysis2 or BF2 .
So my recommendation is based on real world experience and the fact that anything less than a 650w PSU will most likely run hot.


a gtx580 is going to run an extra 30w-80w (3a-7a) then the GTX570. if your corsair tx650 was running above 50c then it could have been an internal issue or an issue with the fan.


October 26, 2011 3:57:28 AM

I think the real issue is the Phoenix Heat! I run my AC unit at 80 during the summer or the electric bill will be huge. Ambient temps probably have a lot to do with it!
a b U Graphics card
October 26, 2011 4:53:58 AM

pffft, 80 degrees.... here in vegas it gets up to 110 regularily.... kinda sucks not having AC in that type of weather :) 

my 5670 (i know not the hottest card in the world) gets to a max of 62c in furmark test of about 2hrs :) 
!