The Fastra II 's predecessor , the Fastra I , have 4 dual @-@ GPU GeForce 9800 GX2 video cards , for a total of 8 GPUs . At that time , the ASTRA group needed a motherboard that had four PCI Express x16 slots with double @-@ spacing between each of them . The only such motherboard the ASTRA group could find at that time was the MSI K9A2 Platinum , which have four such slots . In 2009 , the Asus P6T7 WS Supercomputer motherboard , which the Fastra II uses , was released , which have seven PCI Express x16 slots . The Fastra II have six faster dual @-@ GPU GeForce GTX 295 video cards , and a single @-@ GPU GeForce GTX 275 , for a total of 13 GPUs . In the Fastra II , the GPUs mainly perform tomographic reconstruction . The technique which allow GPUs to perform general @-@ purpose tasks like this outside of gaming , instead of CPUs , is called GPGPU , general @-@ purpose computing on graphics processing units .