You got the wrong power converters
to a bigger extent - you are getting on a long and slippery bodge it trail
the sata converters use molex power connectors (as did the first HDDs) - in this case presumably to save space they've supplied a molex to mini-molex (like wot floppys use) converter
THESE
(can't see any on google - but my PSU still has a couple of "retro" connectors)
so you are right - should have either got one of
them... no THESE
or you can build your own after a trip to maplins
with sata - each chanel is master
the dvd drive - for �15 I'd splash on a new one (fnah)
you also need to realise - the adapters are 100/133 compliant - which just means they are SATA1 - which means they are about 1/3 the speed of a new sata drive.....
and the rule is - that all devices work at the speed of the slowest device - so saving a quid has a cost as well.
(using usb - you won't have this problem)