Hi,
It looks like your heatsink is just a piece of aluminium channel.
You would be better off putting a finned heatsink in the channel as well to move the heat.
Does the COB holder specify any heatsink requirements?
Tom.. 
Hi,
It looks like your heatsink is just a piece of aluminium channel.
You would be better off putting a finned heatsink in the channel as well to move the heat.
Does the COB holder specify any heatsink requirements?
Tom..