GPU upgrade 5750 to 6970M

Hi

I am happy owner of mid 2010 iMac 27".

I want to upgrade my GPU from Radeon HD 5750 1GB to AMD Radeon HD 6970M 2GB.

My question is can I keep heatsink from Radeon HD 5750 1GB and replace just a card ( as this would save me around 100 euro) ?

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