157 Mhz Core is for the Cards, when they are Idle.
Start something which uses the GPU, and it clocks itself up. (Start your Miner e.g.)
For Overclocking, use either Sapphire Trixx or MSI Afterburner.
Greetings, Frog
Essentially I couldn't get them past idle even when trying to mine but I plugged the whole PSU in and that seems to have fixed things. Thanks.