Tentatively it shouldn't be a problem. Though some system integraters do lock out certain hardware changes via BIOS.
Use something like HWiNFO to find out your motherboard model. It's possible to see if anyone has used a different graphics card with it using the Userbenchmark site providing some peace of mind.
EDIT: Also depends on the PSU in the system too, so you'd want to check the wattage of yours.