Question: can pcie 3.0 work in 1.0?
Answer: PCIE 3.0 cards are backwards compatible with the 1.0 and the 2.0 slots, but you won't be able to enjoy the full extent of your new PCIE card. It will be restricted to Gen 1 speed (2.5 Gt/sec) while Gen 3 allows 8 Gt/sec and a better encoding scheme which actually makes it about X4 times faster.