Yeah, you have a little room to overclock. You now have about 8-9c of headroom.
Lower the HT Link multiplier to 9x. You want to keep that frequency between 1800-200 as you overclock so change the muliplier from 10x to 9x. Keep the CPU core voltage at stock for the time being. Lower your ram speed from 1333 to 1066. Then start increasing the CPU frequency by 5 mhz incrments. Stock is 200 mhz so your first increment would be 205. Test with 20 minutes of Prime95 blend after each increase. Watch core temps with HWMonitor. When you can no longer pass the 20 minute Prime test (blue screen, spontaneous restart, lockup, a core worker drops out of Prime) then post back with pics of HWMonitor after the last test and of CPU-z tabs: "CPU", "Memory" and "SPD".