Is it safe to connect between a 24-pin mini ATX on the motherboard to a standard 20-pin ATX connection on a PSU with an adapter? I have an HP Pavilion Slimline s3420f desktop. I cannot afford a new computer. I have upgraded from an NVidia GeForce 6150 LE nForce 430 graphics card to a Sapphire Radeon HD 4650 low-profile graphics card. I wanted a GeForce 9800GT low-profile, but no one has one and I'm unwilling to wait any longer. Along with this upgrade, it was necessary for me to also upgrade my PSU, as my original psu was only 160w None of the PSUs that have the right form factor have enough wattage to do the trick, so I jerry rigged a space in my desk, behing my PC, for my new Corsair TX650w to call home. I then removed the old PSU from the case, and am planning on running the cords from my new psu through the hole that was left in the back of the case upon removing the old psu (the connector cords are more than long enough). However, my plans were messed up when I realized that my mobo does not have a standard ATX connection, its quite a bit smaller. There is an adapter available that connects to the 24-pin mini ATX on the mobo and then goes to a 20-pin standard ATX connection on my psu (my psu has the split 20/4 connection that appears to be commonplace in most of the new units available). I've also contacted a couple of custom cord makers to see if they can make me a 24-pin to 24-pin adapter that will fit into both ends, but I'm still waiting to hear back from them. I know some power is lost with these adapters between the psu and the pc, so it was a good thing I bought a psu with more than what I really need. Can anyone tell me whether or not it would be safe for me to use the adapter? Thank you for your time.
If a system requires an original 20-pin connector then that means it's probably based on the antiquated ATX v1.3 spec. A system that old will draw mainly from the +5V and +3.3V rails, not the +12V like modern systems.
Make sure your PSU has a minimum +5V/+3.3V combined rating of 150W, 180W if it's a high end (for its time) system.