Two of three fan sockets in my brother's motherboard have died. Knowing I was out of my depth, I took the computer in to get repaired, and got it back with the CPU fan plugged into the one working socket going at a constant full speed, and the case fan unplugged. It was recommended that I buy a cable that connects the case fan straight to the power supply, so I've done that, but now I can't figure out how to lower the cpu fan speed, as it is extremely loud... as is the case fan now, because the new cable does not control the speed, so it too is going at full.
All the usual speed control programs (speedfan, motherboard monitor, etc...), on the rare occasion that they do actually read the speed, are unable to change it. The BIOS is useless too.
What do I do???
I'd rather not get a new motherboard for him, as I've just bought him a new hard drive and discovered how update-unfriendly his case is and so bought him a new case too.

You might want to look into variable speed fans. Antec makes them and they come in 3 speeds with a switch that is used to control the speeds. Check out Newegg.

i dont know what type of cpu you have, but we have amd and we got this fan for it

http://www.pcboost.com/store/viewitem.asp?IDProduct=13810

it is big but very quiet and well worth the price(actually it was free cause they sent us the wrong one). just thought i let you know

BIOS speed control is only going to be able to control the speed of fans connected to the fan headers on the motherboard, which have died now. You can either get variable speed fans (which have an inline controller) or buy lower speed fans to replace the current ones.

Dang, ok then, thanks.