Compute single MD5 SHA1 hash on GPU

I was wondering if it is possible to compute a single MD5 or SHA1 hash on GPU more efficiently than on CPU.

I know that there are apps that compute tons of hashes in parallel to brute force passwords. That's not what I'm looking for. I would like to quickly hash large buffers of data.

Looking at the algorithms it doesn't seem possible to parallelize them for efficient GPU computing. But perhaps I'm wrong?