need more information......as your GPU card is very light (6.4GB/s) bandwidth and only a 64 bit card, I think the problem might be that. However you must post all your specs so we can make an informed opinion. How much RAM? How big is the CPU? How many Watts is the Power Suppy? Motherboard full Name?
go here to check out your GPU against other GPU's
Win10/HAF X/CM 1000W gold/Z77X-UD5H/OC'ed 3770k @4.5GHz/32g G Skill/OC'ed GTX780 @1063MHz-6608MHz/850EVO256g/Vertex3 120g/WD 500 Blk/3 x WD 1T Blk
Win10/CM Centurion/650W/Z77X-UD3H/OC'ed 2500k @ 4.1GHz/16g Kingston Hyper X/HD6870/HyperXFury SSD 120g/WD 500 Blk/WD 1T Blk
UBUNTU 15/ AMD @3.2ghz/ GTX460 1g/ 8g Kingston 1600/ 2 x 500g HDD
doesn't keep me up nights, no siree