I have a reasonably-decent old 20-pin PSU which I want to use on a newer 24-pin ATX motherboard.
I see that the
ATX page on wikipedia
mentions that 24-pin ATX is backward-compatible, and I can find 20-to-24 pin adapters to buy for a couple of dollars/pounds at lots of places, but I can't find any mention of restrictions on the use of these.
Will this work on any motherboard, or is it a per-motherboard compatibility question?
Are there any other restrictions like the level of power available (and hence the additional 4 pins with +12, +5 and +3.3V lines which are already on other pins)?
Best Answer
I have no exact information to provide you here, but my gut feel would be that you should only consider trying this if you have a relatively low-power system on the motherboard. Something with not too much memory, ideally no more than 1 hard-disk, and probably not too high-end a dual-core processor... if you have any kind of modern graphics card installed I would probably not even consider going there.
Note that what the 24-pin supply does, is add one additional supply line of +3.3V, +5V and +12V each. If you use the adapter you suggest it will copy one or more of the existing lines to supply these pins... which means that they need to share the additional load.
From having a look at the Wikipedia page you reference, it looks like the standard 20 pins have a decent number of +5V and +3.3V lines already, but there is only one +12V line, which gets duplicated by the extra 4 pins. I do not know offhand what hardware uses the +12V, but that would be my main stability concern when using the splitter attachment.