how to do 20 -> 24 pin adapters work?

[BlahBlahYouToo]

they can't make something outta nothing so they have to draw from somewhere right?

 

[Gillbot]

They just split one of the existing lines.

As you can see in the pic:
http://www.smps.us/atx-connector-20-24pin.jpeg

It has +12, +3.3, +5 and GND. They just branch off of existing leads to make the connections. Honestly though, many mobo's will run fine with a 20 pin PSU plugged into a 24pin header.

 

[HOOfan 1]

If your motherboard runs with a 20 pin connector DO NOT use a 20->24pin connector. If your mobo works with only 20 pins then the adapter is absolutely useless and just adds unneeded resistance and clutter to your case.

What PSU do you have with only 20 pins and what are you trying to power with it....we are talking pre-ATX 2.0 here so it is a pretty old design for a PSU and it might not be powerful enough for a modern system with a powerful graphics card.

 

[BlahBlahYouToo]

Originally posted by: HOOfan 1
If your motherboard runs with a 20 pin connector DO NOT use a 20->24pin connector. If your mobo works with only 20 pins then the adapter is absolutely useless and just adds unneeded resistance and clutter to your case.

What PSU do you have with only 20 pins and what are you trying to power with it....we are talking pre-ATX 2.0 here so it is a pretty old design for a PSU and it might not be powerful enough for a modern system with a powerful graphics card.

it's an older thermaltake (~4 yrs old) 400 watt that was highly rated back in its day.
the motherboard is a 24 pin P45, and the gfx card is a 8800gs (relatively low power, XFX recommends min 400 watt).

 

[HOOfan 1]

I am not sure Thermaltake had highly rated units 4 years ago....

How much current available for 12V?

 

[BlahBlahYouToo]

18 amps, single rail.

 

[HOOfan 1]

That is only 216W That is about equivalent to a 250W ATX 2.0 supply.

I am sure your PSU won't have much problem powering your system, but if you ever want to upgrade to a better graphics card or overclock your processor much. You are going to want to upgrade that PSU.