Pronunciation of "cache"

'Kash' is the correct pronunciation. If you pronounce it 'kash-ey' then you're actually using a different word entirely, cachet.

Here in Australia it is common to hear it pronounced "kaysh". An american friend of mine pronounces it "cash" and I am always aware that his pronunciation differs from the local norm. I can't recall ever hearing "ka-shay" and I suspect @Bacon Bits is correct that it is a conflation with cachet.

IT people, at least in my country, prefer to pronounce "cache" as "cash", like your dictionary tells you. Actually, I don't seem to remember ever hearing someone pronounce it differently.

You are right, 'kash' is how cache is pronounced.

I am not sure any pronunciation would be totally unacceptable as long as they do not cause any misunderstanding. Of course, it would be nice to pronounce it correctly. I have heard the word pronounced as 'cashay', 'catchay' etc. in presentations and meetings, but they have been perfectly understood.