Crucial M4 has been discontinued

Yikes! That would scare me.
Are you doing anything particularly brutal to these drives? Or do you think it is just (very) bad luck?

Not really, I have indexing off, Write cache on, only OS and programs on both. Crucial said it should not have acted that way. Samsung-no reply from them.

Are you using the Microsoft driver. If so, try the Intel RST driver.

Yup, both were on the iastor.sys Intel driver. The msahci is just horrible.

Have you tested one on the SATA II controller. Even if it's not SATA III, the results should still look good for SATA II. If they do, then you can start to question your SATA III controller, it may be bad.

I did that too, on SATAII the numbers are even more sickening, worse.

Well, hope you get it sorted.

Thanks man, I hope so too. So far the new/refurbished M4 is doing fine. sometimes I think I'm a magnet for defective products.

The technician's curse. Not uncommon for techs to get more lemons for unexplainable reasons.