I have mused over just such a concept.
A design I have spent some time considering would involve a nozzel which would widen and flatten to feed the water uniformly over a field of pins.
But, in my mind, I doubt it would:
1. perform very well,
2. reduce cost,
3. ease construction,
4. reduce flow resistance,
5. be possible to mount(ok,
possible but it might be comparable to pulling teeth)
A single round inlet would be easier to make, and might perform a little better but that would depend on the design of the rest of the block.
But here again, in my mind, I doubt it would:
1. perform very well,
2. reduce cost,
3. ease construction,
4. reduce flow resistance,
5. be possible to mount(see caveat above)
To me, the easiest and most practical way to facilitate lateral flow would be to use an L-fitting, but to do so would likely mean to give up more ground(with respect to resistance) than would be gain from lateral flow.
Another possibility, I have considered is 1/4" tubing which would allow all sorts of ways to snake around most anything that would interfere with mounting; but again to do so would likely mean giving up more ground than would be gained from lateral flow.
In my mind, we are then left with either fitting a custom block to each individual model motherboard/system or reducing the physical size of the waterblock.
Again, this is all in my mind so take all of the above as you may.
Is my analysis flawed or does my reasoning sound plausible?