DIGIT-ARC read-only archive · snapshot: July 23, 2026

Dual Rail SMPS:how to connect?

31 posts · originally from https://geek.digit.in/community/threads/dual-rail-smps-how-to-connect.78141/

The_Devil_Himself
The_Devil_Himself Original post #1
Jan 13, 2008 at 3:11 PM
Ok guys time to help this poor noob.I baught following stuff recently:

1.POV 8600gt 256mb ddr3
2.2x1gb ddr2 667mhz RAM
3.A not_so_local SMPS rated 480watts.It has 2 +12v rails,each one having 15amperes(as written on SMPS).It has a 120mm fan and has blue color LED's too.

I have connected my smps without the graphic card,its working fine(very silent).Now my question is how do I connect my graphic card?I mean 8600gt has no power connector,it just drwas power from PCI-e slot.How do I combine both the rails to get 30ampere on +12v rail?Or is it automatic?I am confused.

Here's is my full system specs:
e6300 c2d proccy
Intel 946gzis mobo
2x1gb ddr2 kingston 667mhz RAM
POV 8600gt 256mb ddr3
480watt ICOOL spms with dual +12v rail of 15amperes each
1x80gb sata hdd


Here's is the list of connectors The smps has:

1x20\24pin connector
4 pin for cpu
6 molex connectors
1 PCI-e connector
2 sata ones(I think)
2 connectors for Fans.




Reply asap guys! I need tp play crysis by evening!

One more thing*forums.erodov.com/images/smilies/biggrin.gifo I need to reinstall my windows?or just installing onboard graphics and installing nvidia drivers will do?
H
Jan 13, 2008 at 3:16 PM
You don't have to worry about the Rails.Just uninstalling the driver will do.
The_Devil_Himself
Jan 13, 2008 at 3:18 PM
^^just connect what should I connect and its done?You sure?

You mean rails are just internal thingies,not visible to us?

sorry for being so noobish,but I have no idea about them.
dOm1naTOr
Jan 13, 2008 at 3:18 PM
It'll automatically share the load from the dual 12v rails.
And 8600GT needs only some 17~18A on a 12v rail na? Even 8800GTX dun need 30A on single rail.
And even 400w normal PSU can handle 8600GT. So no worries dude. Just connect it to ur mobo nd everythin ll be fine.
H
Jan 13, 2008 at 3:22 PM
I hope dOm1naTOr answered your questions. :)
Pathik
Pathik #6
Jan 13, 2008 at 3:22 PM
Just connect the 24-pin PSU connecter to the MOBo. You don need to power ur gpu externally.
The_Devil_Himself
Jan 13, 2008 at 3:24 PM
thanks harvik,dominator,and pathik.I have already connected all the connectors including 24pin one.And yea 8600gt needs about 18-20amperes on +12v rail.Had to buy this SMPS cos they quoted Rs2k for Zeb. platinum 500watt,400watt platinum wasn't available.Simple Zeb. 400watt was Rs.350 but I don't trust it much.Coolermaster 500watt was Rs.3.2,way out of my budget.Baught this current one for Rs.1.4k.I guess a bit costly but it was what was available and I cudn't wait any longer.It has a120mm fan and blue LED's too and came with 1 year replacement warranty.

oh wait
One more thing, do I need to reinstall my windows?or just uninstalling onboard graphics drivers and installing nvidia drivers will do?My mobo disables onboard graphics automatically when an external card is connected(no bios setting needed)
what about this?
Pathik
Pathik #8
Jan 13, 2008 at 3:32 PM
Depends. If u may get a BSOD or something after booting into windows then u may need to reinstall.
Try and say.
BTW try this.
Remove the intel onboard graphics drivers and then attach the gpu and boot.
The_Devil_Himself
Jan 13, 2008 at 3:34 PM
^^oh ok,I will be abck after a while(I need to back up some data too incase something bad happens)


I am back and something very bad has happened.:(.why always me.

I connected the graphic card in my mobo's PCI-e slot,the PC din't boot for like 5-6 times,then it did boot up,I installed nvidia drivers(I had already uninstalled onboard graphics drivers beforehand),installed crysis,and then I tried restarting,The PC din't boot up!!!(No signal, going to sleep) I tried for 10-12 times(trying all the combinations of dvi+vga,The card has dual DVI port and two dvi-vga connectors are also given, and my moonitor has 1 DVI+1VGA port.).I removed the card and The PC booted normally on onboard graphics!!!.At this point I thought it was some connector(dvi-vga) or cable problem,so I tried replacing them but nothing happened.I tried booting after removing dvd-writer and HDD but it din't boot up.After trying for about 2 hours it did reboot on graphic card and I RAM gpu accessment test(crysis inbuilt),I tried to reboot again to make sure its all right then but I was worng It hasn't booted on graphic card card since then.I am back on onboard now for trying for like 4-5 hours:(

1.RAM isn't damaged for sure.
2.Processor-nada
3.Graphic card-It ran smoothly everytime The PC booted on it.SO I am sure its workig alright.
4.SMPS:well I am not sure but it shouldn't be faulty as MY PC is running fine right now.And I did try booting after removing HDD andf DVD-writer so power isn't a factor in not-booting I guess.
5.Motherboard-Sucky Intel 946gzis,it is too working fine right now on onboard.
6.PCI-e slot?well I don't know.


so what do ya guys think is happening?I can't believe it happens to me all the time,sux!
The_Devil_Himself
Jan 14, 2008 at 6:50 PM
no suggestions?

I tried today too,same sh!t ,only booted once in maybe like 10-15 tries.:(
dOm1naTOr
dOm1naTOr #11
Jan 14, 2008 at 7:03 PM
Clear the CMOS by the jumper method.
Is there a seting on bios like the device for display first? There wud be choice like onchip VGA, PCI, PCIE etc. Set it to PCIE. And disable onboard display in bios if there is any seting like that.

And by'not booting from gcard', does the loading of windows showup? And POSt screen displays?
The_Devil_Himself
Jan 14, 2008 at 7:34 PM
Thanks for replying,Lemme answer one by one.

1.cleared the CMOS and tried,nothing.

2.No setting in BIOS,I had read the manual which says it is automatic i.e The mobo itself changes from onboard to g.card.I have a Intel 946gzis BTW.

3.No,The screen doesn't even show BIOS splash page.
By 'Not booting from gcard' I meant the screen shows "No signal,going to sleep".

I tried using Ubuntu Live Cd but the same randon results--booted sometimes(I cud see the drive's LED blinking) and nothing other times.It was random cos when I re-powered the setup again without even touching it din't boot up the next time.:(.
H
Harvik780 #13
Jan 14, 2008 at 8:23 PM
It might mean that one of the 12V rails is totally dedicated for the CPU which might result in lower power to the GPU due to which it isn't booting.
It sometimes does due to power fluctuations in the PSU.
Or it might mean that the card is bad.
Do you have any friends pc on which u can check the Graphics card.
harryneopotter
Jan 14, 2008 at 8:34 PM
ravi ... jab maine sunny se liya hua card apne pc me lagaya tha ... i also faced the same problem .... my pc was booting on onboard grfx bt nt on 8600gt ... i though the connecter (DVI TO VGA) was faulty ... so checked that at my friends place and it was perfectly fine .... then i changed bios settings (first by removing battery, thn by changing dsplay mode to PCI-E from onboard), nothing happened ... then i plugged the connector again (forcefully this time ) ... and it started .....and from that time onwards ..its working perfectly fine.........

and i forgot to mention that the PSU i am using is the default 400w which came with my cabby i.e. Zebronics Shivaji (cost Rs 1250 last year march ).
The_Devil_Himself
Jan 14, 2008 at 11:56 PM
^^
1.My monitor has both DVI and VGA input,and I have tried them both.:(
2.What do you mean by not booting up?
harryneopotter
Jan 15, 2008 at 11:51 AM
oh sorry i mean ....sustem was booting ...but there was no display, no post or anything ..the monitor light was blinking..thts it.......
The_Devil_Himself
Jan 15, 2008 at 5:19 PM
^^thas the difference,my system doesn't even load bios or anything(I have tried with live cd).
harryneopotter
Jan 15, 2008 at 6:05 PM
mean no cpu lights(LED) ? cpu fan not running ? Card fan nt running ???
Ranjya
Ranjya #19
Jan 15, 2008 at 7:04 PM
Does it beep on start.
If not get a new BIOS battery.
H
Harvik780 #20
Jan 15, 2008 at 7:10 PM
I am pretty sure its a PSU problem because of that no name PSU and the fact that your computer does not have any beeps when not booting.
Please i emphasize that you return that PSU saying that its not enough for your system of maybe its not a true power.
H
hellgate #21
Jan 15, 2008 at 7:24 PM
clean the pci-e slot and then try connecting the card.if prob persists then try with a diff psu 1st and then with a diff gfx card.
vivekbabbudelhi
Jan 15, 2008 at 9:18 PM
im just curious from whom did u bought that smps in NP & wasn't CM 380w available??
dOm1naTOr
dOm1naTOr #23
Jan 15, 2008 at 10:37 PM
Zebronics 400W normal can easilty handle ur rig. Get one for 400 bucks nd return this.
harryneopotter
Jan 15, 2008 at 10:58 PM
+1 for arvind's suggestion ..
The_Devil_Himself
Jan 17, 2008 at 5:25 PM
ok guys thanks for your suggestions,I am getting this PSU changed ASAP(this weekend most prolly).


This is what happened yesterday(cudn't post yesterday cos my net sucks.Life in general sucks).

Since I can't just sit and see my 8600gt lying around on my table,I tried it for the last time,This time recording every observation in minute details like a true scientist.

I tried my default PSU(I won't tell its wattage,you guys will laugh.This is a Zenith OEM PSU),ANd tried booting with G.card,no display but it was booting up from XP+vista+ubuntu discs normally(I can see from the drive's blinking LED).I then tried with the new PSU,same thing as above.I restarted several times waiting for some miracle,ANd yea it did happen,It booted with the g.card!.I installed drivers,and restarted.It did boot up again normally.(I didn't even touch this set-up to make sure nothing escapes my eyes).I installed Soldiers of fortune,and played it a bit.Then I installed gears of war(Bugger took about an hour to install and took up 10gb space).The played it a bit to make sure card is working fine.Then I restarted it several time without touching anything except the on\off keys of UPS.Then I tried changing the dvi cable's ends to make sure it's ok,It worked like a charm(DVI>>>VGA,it so much more clear).Then I thought its all fine and now the PSU should be put in its' position.but voila as soon as I fixed the PSU in its place in Cabby(I am 100% sure I din't touch g.card or power connectors or anything).It hasn't booted up on g.card since then.It happened just after I positioned PSU on its position in cabby.

pretty long story,eh?lol.SO what do you guys think now?I am sure g.card is working all right.I checked using gpu-z some other tools.I think its either my Mobo or the psu.But the mobo works fine on onboard video.Is it that that PSU delivers sufficient power sometimes and sometimes not?Or that its got some loose connections?Problem is I got only about 2k rupees so I can either get a better PSU(after returing this one) or add some more to get a new low end c2d mobo.:(


And yea It does boot up everytime,its just that display doesn't get any signal,maybe the g.card doesn't get enough power i guess.

This is all so confusing.dammit.

so what do you guys say now?
Pathik
Pathik #26
Jan 17, 2008 at 8:27 PM
Dude get a 500w zebby normal PSU if u dont have enuf cash. Even that ll work fine. around 0.5k
The_Devil_Himself
Jan 20, 2008 at 12:53 PM
ok guys got a new PSU in replacement+cash,zebronics 500watt platinum,But the same problem persists.WHat now?I am really fed up with this ****.I think I should sell off this 8600gt of mine and be content with onboard.:(.

Can my mobo\Pci-e slot be at fault by any means?


My net sucks too,no connectivity after 5:30-6pm.
H
Harvik780 #28
Jan 20, 2008 at 1:58 PM
Get the card replaced.
Choto Cheeta
Jan 22, 2008 at 11:01 PM
I guess the board still Under RMA, Ravi send the board for RMA for a faulty PCI-E slot... Man D946GIS would be better than 610i board :( try to short out the problem rather than buying a New one...

I hope you know the process to obtain direct support from Intel rather going via any dealer :)
The_Devil_Himself
Jan 22, 2008 at 11:02 PM
^^not under any warranty,this was a Zenith OEM and zenith provided only 1 year warranty.


sorting out problem:
1.processor:nah
2.hard disk: nah
3.RAM:nah
4.CARD:not IMO,it worked flawlessly whenever my PC booted on it.
5.PSU:not anymore.
6.Mobo:I guess its the culprit.
7.whatelse?