# Connect 24 pin to 20 pin on motherboard



## jolive (Mar 5, 2008)

can a 24 pin power supply be used with an older 20 pin motherboard connector? Is there an adapter to convert the 24 to a 20 pin? 

I need to know rather quickly since my PC is open and I just found out that the power supply I am replacing is a 20 pin.


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## 1 g0t 0wn3d (Jan 31, 2007)

yes you can 4 will hang over and it is keyed so that you can not put it in wrong


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## jolive (Mar 5, 2008)

Are you saying to just use the 24 pin that is on the powersupply to plug directly into the 20 pin on the motherboard and that an adapter is not needed?


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## 1 g0t 0wn3d (Jan 31, 2007)

yes i am, same concept for the 20+4 connectors only the 4 does not come off


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## speedster123 (Oct 18, 2006)

whats 20 pin? the motherboard or power supply?


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## jolive (Mar 5, 2008)

The 20 pin is on the motherboard. But I have an update. I had to buy a 24/20 adapter because there are capacitors next to the connector on the motherboard that will not allow plugging the 24 pin directly. However, other issues came up. 

The reason I was putting in a newer power supply was that I got a newer video card that requires separate power and a minimum 300 W power supply.

My existing system is a Compaq with a 200 W power supply with 4 4-pin power connectors. I also have two hard drives, a CD Writer and DVD player. So, I have 4 existing devices plus 1 new device (video card) that require a 4-pin power connector for a total of 5 devices hungry for power.

I took a 300 W power supply from a Gateway PC that I had upgraded to a 500 W ps and installed it into the Compaq. However, the Gateway ps only has 3 4-pin connectors plus 3 SATA connectors. So I put the 300W ps where the 200W ps was and moved the 200W to another location in the case (much use of Dremmel tool required). My idea was to use both power supplies to supply the power required.

So I powered the video card with the 200W supply, the CD, DVD and one HD from the 300W ps, and left the C: drive which I had erased with no power. When I put everything back together and turned on the power the PC started beeping and a warning appeared on the monitor in red letters that said the video card was not receiving power. Well I know that it was receiving power because it was plugged into the secondary ps, but the BIOS evidently did no recognize it. 

I then put the old video card back in and plugged everything back into the 200 W ps. I discovered that I had connected the communications ribbon primary HD connector to the D: drive that was formerly the slave drive. I suspect that I forgot to change switches on the drive to correspond to the connector because when the system came up it was trying to access the C: drive and could not find an OS. 

So, now I am just trying to get the PC to boot from my D: drive which has Win XP Pro loaded and drop the old hard drive; and this long story comes down to how I find out the right switch adjustment to make my D: drive the primary so I can connect it to the primary IDE connector and have the system boot correctly...


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## jolive (Mar 5, 2008)

Update: I disconnected the smaller hard drive to cut down the confusion. The remaining drive which was D: now became C: and had the right switch setting: cable select; and I connected to the primary connector on the IDE ribbon. I kept getting "Error loading OS" message and it would not load the OS. So I loaded XP Pro again and the system knows their are two instances of XP but only will boot to the new one. Also, I can see the old programs in Program Files folders but they will not load. 

I can delete the old programs, just can't access them, so I will do that and then try to get rid of the original XP install.


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## jolive (Mar 5, 2008)

Update 2: I learned that you Cannot use two power supplies. If the power supply is not connected to the motherboard it will not power up. So I connected the larger power supply and used Y power connectors to attach to the devices.

I then formatted the hard drive to completely start over with a clean slate. The video card is now powered and so far everything is working very well.


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## Thething (Feb 6, 2008)

I know its solved and a little off topic but there is a way to use 2 PSUs with a system although its not recommended if your not sure what your doing. Using a spare piece of copper wire you can hotwire the powersupply 24 pin connector so it thinks its plugged in a motherboard and will power up. I cant remember how to do it exactly as I havent done it in a long time but as i remember it you stick 1 end of the copper wire in the black earth pin and the other end of the wire into the green pin, then just plug it in, plug something into a molex and hit the switch:smile:.


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## linderman (May 20, 2005)

Thething said:


> I know its solved and a little off topic but there is a way to use 2 PSUs with a system although its not recommended if your not sure what your doing. Using a spare piece of copper wire you can hotwire the powersupply 24 pin connector so it thinks its plugged in a motherboard and will power up. I cant remember how to do it exactly as I havent done it in a long time but as i remember it you stick 1 end of the copper wire in the black earth pin and the other end of the wire into the green pin, then just plug it in, plug something into a molex and hit the switch:smile:.




you are correct however, I would not feed video cards off any power supply not connected to the motherboard


you could use the extra or second power supply to power up the hard drives and cd-rom drives but I wouldnt fire the video card off it


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## jolive (Mar 5, 2008)

Thething said:


> I know its solved and a little off topic but there is a way to use 2 PSUs with a system although its not recommended if your not sure what your doing. Using a spare piece of copper wire you can hotwire the powersupply 24 pin connector so it thinks its plugged in a motherboard and will power up. I cant remember how to do it exactly as I havent done it in a long time but as i remember it you stick 1 end of the copper wire in the black earth pin and the other end of the wire into the green pin, then just plug it in, plug something into a molex and hit the switch:smile:.



What is a "molex"?


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## linderman (May 20, 2005)

molex is the four pin power plug seen here

http://en.wikipedia.org/wiki/Image:Molex_female_connector.jpg


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