Is it compatible?

[neo.miggy1605]

Is a 980 ti graphics card compatible with my memphis2-s mobo?

 

[bjornl]

It should work with the motherboard as it has a compatible slot. Bigger question is the powersupply. The 980ti needs a fairly beefy one and by default HP uses low wattage ones. You should probably have a 600w PSU to run a decent system which has a 980ti in it.