Not sure if this is the correct section please move if innaproriate. I have two ASUS EN7800GTX they overclock to about 490/1310 I'm happy with that

I have bought two Artic Cooling 5 rev 3 and I was wondering if it is possible/worth it to replace the thermal pads with ceramique. 3Dmark 05 benchmark is lowish @ 10300 stock 10800 overclocked as above... I have AMD 3500 ( newcastle core ) on ASUS A8N SLI premium is this why? Should I bite the bullet and watercool them which coolers are good?