cpu heatsink issue

Hi everyone,
I recently purchased 13 intel heatsinks with fans for a vero 18 build.
The issue is the heatsinks have a raised circle in the middle that would of sat on the processor in the pc. Well this raised circle doesnt quite cover all of the square metal part on the back of the vero, it leaves the corners sticking out with no contact. I know its probably hard to imagine what i mean but if you drew a circle inside a square and imagine the circle is the heatsink and the square is the back of the vero. Will the heat sink draw enough heat away contacting about 90% of the back of the vero or am i better off scraping them and getting some new heatsinks.
Thanks andy

Can you plane the raised part of the heatsink using a sheet of glass and progressively finer grit sandpaper? Wet sanding...

Not worth the effort mate, sanding that much stuff is PITA by hand and they are very hard to get totally flat. If you have access to a mill then why not. I had those same style heat sinks, btdt.

Hi snaps that might be possible but it would be alot of work as the raised part is about 6mm. I think it would probably need grinding or milling flat.
thanks andy

Yeah 6mm is a bit much. Lol

Thermal epoxy a aluminum square on it. Use that as a base instead

Thanks for the advice,
Epoxying an extra square of aluminium between the vero and heatsink sounds like it would work, but would it have much effect on junction temperature due the additional layer of thermal epoxy.
I have seen some reasonably priced xilence l240 heatsinks and fans and am considering using those if they are suitable, if i cant make good use of the intel ones i have.
Thanks andy.

they work well together. i have a vero 29 running at 75w with
the same heat sink. IME all that matters for thermal conductivity
is the metal piece on the back of the COB. the thermal junction
on mine gets up to 70C in an hour and a half and stabilizes there.

Before buying new sinks I would likely do some testing first. Those heat sinks were probably designed to extract more heat than a Vero 18 is putting out. My guess is that 90% contact will be plenty.

Thanks for the help everyone. I have decided to attach the vero 18s to the underside of a piece of 4"x1" aluminium u channel, i will thermal epoxy the intel heatsinks with fans to the rear directly above the leds. My thinking is that the extra surface area of the 3mm thick aluminium being blown by the fans, should more than make up for the additional layer of arctic silver thermal adhesive. Also it might add in a little safety margin should a fan fail.
Thanks for the all the help and advice.