I have an i7 950 and need a board for it, i7 is LGA 1366 and seems it is hard to find a mobo for it.
Would socket 1150 work for i7 950?
or socket has to be LGA 1366?
Your i7 950 is a socket 1366 chip and will only work in a socket 1366.
Basically this means that unless you can find a second hand motherboard, it might be cheaper to use a more modern motherboard and a matching CPU.
Which CPU will vary. In most cases a modern i5 should easily match the performance of that i7 950. If you need massive parallel processes cheap out the AMD CPU's. On those the single threaded performance is significantly slower than comparable Intel CPU's, but if you can use 8 cores then they provide excellent performance for their price.