Unfortunately this setup is not completely working; only 2/5 cards mine (may be a result of bad extenders or b/c they're not molex powered, but let's assume not for the purposes of this thread).
This is a serious issue and I wouldn't leave it running like that indefinitely, you can be damaging something.
There are posts on this forum discussing how much power is required by the PCIe Bus feeding the cards, which I believe is, from the PCI spec, "125 watts", I think, so that means while each core is drawing 30 watts, 5 * 30 = 150, you're trying to draw more energy than the system can supply over the PCI Bus.
Second issue with extenders/risers; You are adding more distance but adding more resistance and small wires which handle less total current, which contributes to an energy imbalance in the Graphic Cards. Once you go from 4 cores to 5 cores, you need to use powered extenders/risers unless you intend to undervolt the Graphics Cards.
With an imbalance, a card or two may get energy spikes that could damage the graphics cards. They still might hash, but lose overclocking ability.