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20 Pin vs 24 pin

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  • Power Supplies
  • Computer
  • Components
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Last response: in Components
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June 1, 2006 4:24:15 AM

Hey all, I was wondering if someone could answer a question for me. I bought a new computer and needed to up the power supply. The motherboard takes a 24 pin main connector. The PSU that I was going to use has a 20 pin main connector. Can I still use this power supply if I just use 20 of the 24 pins? It is a 480 Watt Thermaltake PSU.

More about : pin pin

June 1, 2006 4:37:35 AM

absolutely not..


get a new PSU, the 20 pin PSU is outdated and wont support ur mobo
June 1, 2006 4:40:25 AM

Yes.

Better to get a 20 --> 24 pin adaptor.
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June 1, 2006 4:45:20 AM

So , There are 20 to 24 pin adapters? There is nothing wrong with the power supply other than it doesn't have 24 pins? So I HAVE to get either an adapter or a new PSU, because what I have right not WILL NOT work, am I getting this right?
June 1, 2006 4:57:04 AM

Some boards allow a 20 pin to run as long as you have the 4 pin power cable plugged into the board also. Check the manufacturer or just try and see. As long as the board isn't propriatery you won't toast it.
June 1, 2006 5:01:15 AM

seeing how old this PSU may be since its not 24-pin native i would get a new PSU. u can pick an Antec SmartPower 500w which is better than ur Thermaltake for around 70 bucks. the 450w Antec Smartpower would do it too.

what are ur specs?
June 1, 2006 5:24:06 AM

Yeah, lets see the specs, I've run athlon 2600's with radeon x850xt pe's, 1 gig ram, and a couple of hd's off high quality 300's with no probs. Even if it is 24 pin, it doesn't mean it needs more power.
June 1, 2006 5:37:07 AM

Quote:
absolutely not..


get a new PSU, the 20 pin PSU is outdated and wont support ur mobo
20 pin will work fine as long as the person is using integrated grpahics. The 4 extra pins are used to power the pci-E slot.
June 1, 2006 5:46:38 AM

not necessarily. if his mobo is 24 pin and he has to plug in the additional 4 pin 12v plug im pretty sure it wont run. not enough power.
June 1, 2006 5:49:46 AM

I've seen both msi and asus boards that ran with just the 4 pin and 20 pin even though the manuals said to use 24 pin, with pci-e graphics cards using a 4 pin molex to 6 pin pci-e adapter. Like I said, it's manufacturer and model dependant.
June 1, 2006 5:58:40 AM

hmmm, i still wouldnt do it. its 24 pin for a reason. probably stability and u dont wanna play russian roulette with my PC.
June 1, 2006 5:59:56 AM

I agree. On the Biostar TForce 6100 mobo I was using, I ran a 20 pin psu on it while I was using its integrated graphics. Just the 20 pin connector and the 4 pin cpu connector were all I needed for it to work fine. I'm sure that if I tried to use a pciE card with it I would have been SOL if I didn't first upgrade to a 24 pin PSU or at least a 20 to 24 pin converter.
June 5, 2006 12:26:53 PM

I have an Asus mobo with 24 pin connector, which I run on a 20 pin PSU without 20/24 adapter. I also have a PCIe card installed, although it is not one of the most power hungry cards (7600GT), so it doesn't require any extra PCIe power connector. Anyway, a 20/24 adapter isn't going to do anything for your performance, it will only cover the 4 extra pins, and there will still not be anything connected to those 4 pins.

I will say though, just because it works doesn't necessarily mean it's a good idea. I plan to upgrade to a more reliable PSU soon. A modern PSU obviously should have a 24 pin power connector, and at least dual 12V rails.
June 5, 2006 1:13:53 PM

I built a new pc recently and realised much to my dismay that the power supply from my old PC 550W Antec was a 20 pin PSU. My new mobo was 24 pin + has the additional 4 pin connector. I just bought a 20-24 pin adaptor and it works absoultely fine. In addition i am using a graphics card that requires external power.

In conclusion, i'd ssay don't waste money on a new PSU if you think the one you've got is powerful enough for the job. Just buy an adaptor, mine cost £2.99 around $5.

Just to add to what i've said, i HAD to get the adaptor as my mobo wouldn't allow the 20 pin PSU to fit into the 24 connector. If this is the case, then trust me, an adaptor will do the trick.
June 5, 2006 2:16:08 PM

The extra four pins in the 24 pin EATX power connector are not in there just for the PCI-e slot...

They provide more path to the exisiting 3.3v, 5v, 12v and ground paths. An adapter just does the trick to make the connection, but it's just composed of briged wires, they don't come from a different rail in the power supply, even coming from a big path in the psu pcb.


As others have said, even if it works don't means that is working with "clean" and stable power. I recommend getting a psu with native 24 pin EATX plug.

And as a disclaimer: There are mobos outhere that don't really need the extra paths and still use 24 pin connectors just for a matter of following the standards.
June 5, 2006 2:17:37 PM

Ok people you dont need a 24 pin psu UNLESS you have two graphics cards. IF you have 2 graphics cards you need a 24 pin psu a 20 to 24 adapter might work but its not a good idea. I dont know about a mobo not working unless it has a 24 pin psu mine worked fine for a whole year, 420w 20pin psu that came w/case and a pci-e 16x ati x700pro video card

The reason for the extra 4 pins are for the 2nd graphics card and the extra power that another card will draw. A 20 to 24 pin adapter might work if you dont have a lot of stuff hooked up that uses 12v.

My psu is a 680w sli ready psu, it has two 12v rails and the reason for this is when you hook up two graphics cards. With only one 12v rail 2 cards plus all the other computer hardware can over load it so they put out 24 pin psu's with two 12v rails one just for the two graphics cards.

my psu has a 20 or 24 pin connecter on it (the extra 4 wiers detach for use with a 20 pin mobo), and for the extra 4 pin that is located else where on the mobo that is 12v also, my psu has an 8 pin connector because some mobos I guess need a sh!t load of 12v to run right. link below is to my psu if you want to check it out, newegg has nice pics of every connecter it has and it has about every connector known to man on it

http://www.newegg.com/Product/Product.asp?Item=N82E16817148020
June 5, 2006 2:26:33 PM

Quote:
The reason for the extra 4 pins are for the 2nd graphics card and the extra power that another card will draw. A 20 to 24 pin adapter might work if you dont have a lot of stuff hooked up that uses 12v.


For your statement to be true, the four extra pins would be composed of 12v wires, they aren't.

4 pins, 4 wires. A Black, a Yellow, an Orange and a Red one. This means Ground, 12v, 3.3v and 5v paths...


Maybe these extra wires are going to the PCI-e slot power fets TOO, but not only.
June 5, 2006 2:36:33 PM

It was not a case of my 20 pin psu not working on the 24 pin mobo, it was simply a case of it not clipping/fitting into place. All i know is that i bought at an adaptor so i have the 20 pin pin psu through an adaptor powering my psu, a 4 pin for my cpu. A 6 pin i believe for my graphics card and all the other usual ones. Not had any stability issues or suchlike.
June 5, 2006 2:58:41 PM

Quote:
The reason for the extra 4 pins are for the 2nd graphics card and the extra power that another card will draw. A 20 to 24 pin adapter might work if you dont have a lot of stuff hooked up that uses 12v.


For your statement to be true, the four extra pins would be composed of 12v wires, they aren't.

4 pins, 4 wires. A Black, a Yellow, an Orange and a Red one. This means Ground, 12v, 3.3v and 5v paths...


Maybe these extra wires are going to the PCI-e slot power fets TOO, but not only.

yes you are correct, I guess I shouldnt have sounded like that was the only reason, but that is the main reason and realy the only one that is of concern.

I dont remember where I got this from but I looked this up a year ago before I got my mobo that has a 24 pin connector on it. what I found was a specification on the 24 pin mobo and a general explination of what all the wiers were for. the extras did some non critical stuff but the one thing that was on that list was sli graphics and that a true 24 pin psu not a 20 to 24 pin adapter was highly recommended if you were to run sli because the extra 12v. I will see if I can find some good info on the 24 pin psu thing then post it in this forum or start a new one to explain it.
June 5, 2006 3:31:28 PM

Ok got some info for all of you people wondering about the 24 pin psu thing

This link is to the ATX12v version 2.2 specifications. It is a PDF file so get adobe to view it
http://www.formfactors.org/developer/specs/ATX12V_PSDG_2_2_public_br2.pdf

this is a short quote from it that is most relevant to this particular discussion however I suggest giving the whole spec a once over

“1.2.2 Main Power Connector:
The 2x10 main power connector has been replaced by a 2x12 connector. This was made to support the 75 watt PCI express requirements. Pinout assignments are based on the SSI recommendation.

With the added 12v, 5v, and 3.3v pins the need for an Aux power connector is no longer needed and guidance for this connector has been removed”

And this link is a Toms hardware article about it. its kind of old, but hey it will do

http://www.tomshardware.com/2004/12/23/more_performance/index.html

hope this was of some help
June 5, 2006 3:38:28 PM

Quote:
Anyway, a 20/24 adapter isn't going to do anything for your performance, it will only cover the 4 extra pins, and there will still not be anything connected to those 4 pins.


no, if it was whats the point or getting an adapter? so it looks like its 24 pin?

the 4 extra pins have a job of carrying more power
June 5, 2006 3:42:20 PM

That's true, but if you only need some more 12v juice, just use the now depricated p4 connector inplace of the 24pin. I have had two boards both ssi that NEEDED the 24pin plug and they were both dual opty boards. Never had an a64 board NEED the 24pin.
June 5, 2006 11:10:07 PM

I just decided to go out and buy a sweet PSU, 500W, with some wicked cable management and a button on the back to control the fan speed. I decided to be safe rather than sorry. I do appreciate all the help. My computer is up and running nice and stable!
June 5, 2006 11:15:21 PM

it was a Powmax PSU wasnt it?

:) 

jk what PSU?
!