Fancy ram heat spreaders are mostly marketing.
Ram needs NO cooling at all unless you are looking for record seeking ram overclocks.
A caveat on adding ram:
Ram is sold in kits for a reason.
A motherboard must manage all the ram using the same specs of voltage, cas and speed.
Ram from the same vendor and part number can be made up of differing manufacturing components over time.
Some motherboards, particularly AMD can be very sensitive to this.
This is more difficult when 4 sticks are involved.
That is why ram vendors will NOT support ram that is not bought in one kit.
Ask yourself...
What is my plan B if the added two sticks do not work with my original 2 sticks??
My suggestion is to buy a single supported 2 stick kit of the size...