....
Can I ask you what drivers/overclocker are you using mate? got a rig with 2 FTW3 and 4 SC Black and I can't get them past +70 on core/+300 on memory, they get crazy. And btw got them at your same temps :|
Temps (throttled @ 65) are a bit of a problem lately, summer is coming.
Using (Ubuntu) Linux, latest driver available (ppa:graphics-drivers/ppa). No special overclocker, just the settings below.
DISPLAY=:0 /usr/bin/nvidia-settings -a GPUGraphicsClockOffset[3]=85 >/dev/null 2>&1
DISPLAY=:0 /usr/bin/nvidia-settings -a GPUMemoryTransferRateOffset[3]=850 >/dev/null 2>&1