Dell Inspiron N5010 AIT 1GB GPU thermal pad thickness ?

Hi,

I have Dell Inspiron N5010 with GPU overheating issue, fan always working at highest speed but GPU temperature did not decrease bellow 67C and computer shut down when playing games.

Already replaced CPU thermal paste and CPU temperature dropped from 88C to 52C but GPU temperature did not drop so I want to replace thermal pad because it looks like that thermal pad damaged and there is a gap between GPU and thermal pad which attached to heat sink.

online sellers have different thermal pads thickness and they range from 0.5 mm, 1 mm, 1.5mm, 2mm to 2.5mm  

Form what I understood if thermal pad too thick it wont help to reduce GPU temperature so please can you advice me which thermal pad should I use for Dell inspiron n5010, mother board type CN-052F31, dg15 mb 48.4hh01.011 bios, AIT HD 1GB GPU.

Thank you very much

Regards,