You may want to read the last phrase of my comment.
> I find "high-end graphic card (~$500) can compute 10 billion md5 hashes per second" a bit unbelievable
And yet those are the numbers oclhashcat lite publishes for 0.10 on a stock Radeon HD6990 (10886.3M c/s): http://hashcat.net/oclhashcat-lite/
> Yes I realise that md5'ed password strings aren't random
Which is the whole point, and the knowledge the tools I mentioned use: https://community.qualys.com/blogs/securitylabs/2012/06/08/l... (note: the article is about sha1 hashes — which are about 3 times as expensive to compute as md5 — and is done on an older CPU, not GPU-assisted hashing)
> Just saying.
Just saying absolutely nothing?