atx connector question

jonnyb

Just had a new motherboard bundle delivered. in the middle of fitting it I spotted it had a 24pin atx connection. My existing power supply has a 20 pin connection.
Is there any chance that my 20 pin connector will work ?

mboard is a winfast6150m2ma

-TangleFoot-

jonnyb wrote: »

Is there any chance that my 20 pin connector will work ?

Theoretically it will work, though it's not recommended:

You can plug a 20 pin ATX power cable into a motherboard with a 24 pin ATX connector. The image above shows the 20 pin power cable plugged into a 24 pin motherboard (I don't actually have a 24 pin motherboard laying around so I used a circuit board which uses a 24 pin ATX connector). A 20 pin power cable only fits into one end of a 24 pin motherboard connector so you can't insert it incorrectly. The 24 pin motherboard connector is actually just the 20 pin connector with 4 extra pins added on the end. The original 20 pins were unchanged. The extra 4 pins are not separate rails. They're just extra lines to provide more current to the same rails. On every 24 pin motherboard I've seen, the extra lines for ground, 3.3, 5, and 12 are just connected to the other lines on the same rail from the 20 pin connector. I've never heard of exceptions and it doesn't make sense for motherboard makers to create any. As a result, you can plug a 20 pin cable into a 24 pin motherboard and it will work just fine. At least, it will for a while. They added those extra 4 pins for a reason. When you plug a 20 pin cable into a 24 pin connector you're not providing the extra current carrying capacity which may be needed by the motherboard. If your motherboard's current requirements are low enough then it will work properly with only a 20 pin power cabled plugged in. But if the motherboard draws enough current, then you can overheat the 20 pins you're using on the 24 pin connector. I've seen enough pictures of burned ATX main connectors to assure you that this happens. In adding the extra four pins, 3.3 volts went from 3 to 4 lines. 5 volts when from 4 to 5 lines. 12 volts went from 1 to 2 lines so its capacity doubled. Connectors really do get hot if you overload them so the safest thing to do is use a real 24 pin power supply on a motherboard with a 24 pin connector. Note that your 24 pin machine may work fine with a 20 pin power supply until you add a PCI Express card later on down the road. PCI Express cards can draw up to 75 watts through the motherboard connector so adding an expansion card can substantially increase power draw through the main power cable. Many PCI Express video cards which have the 6 pin or 8 pin PCI Express power cable still draw a substantial portion of their 12 volt load through the PCI Express slot. The extra 4 pins doubled the current capacity of the 12 volt rail so that one is easy to overload when only using a 20 pin main power cable.

totalsolutions

Dont you have a 4 pin (2x2) that you "lock" onto the 20 way connector? Its shown in the photos from -TangleFoot-

jonnyb

didn't have the extra 4 pin to click on.
did try existing connection but would not power up, so bought a new power unit with a 24 pin connector.
and also bought a new case for the new motherboard.

it powered up but I could not get it stable - kept blue screening and rebooting. Not had time to tinker with it again yet.

I'm trying to use my existing hard disk, with windows xp installed.

-TangleFoot-

jonnyb wrote: »

I'm trying to use my existing hard disk, with windows xp installed.

As you've changed the motherboard, you'll have to reinstall Windows. A repair installation might be sufficient, but for best results you should wipe the disk clean and install from scratch.

• Clean install procedure for Home Edition
• Clean install procedure for Professional Edition

jonnyb

Thanks for reminder about repair install Tanglefoot. Worked perfectly. I then spent 30 mins trying to work out why the internet did not work, before realising that I had not installed any drivers from the mboard cd. That included the ethernet driver.

Just waiting for internet explorer to download sp3 for ie7 now, as repair install left me with ie6 !

Using firefox to send this reply.