Black screen for 2 seconds - Every so often

[Plec]

How old is your monitor?

If it has display port options you could try testing them.

I was looking at this Prevo DP14-2M on eBay for £7 but others seem to be selling it for £10+

OCUK don't appear to have any dearer ones at the minute

Pick up a standard cable - just to rule it out. Doesn't have to be premium.