Try 459-460 RI. On 270X 4Gb it gives best speed.
What's RI where do I set that?
Go to the Devices tab > choose the Cryptonight algorithm and you will see them. Check my post, that's up a bit, the 2nd imgur link

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Ah you mean Raw Intensity? I'm new to this software

but anyway if I set that over 128 I get not enough memory error.
Yes RI - Raw Intensity.
For cryptonight algo (Threads =2, Worksize = 8 ):
RI = 128 needs 4,3Gb VRAM. And 128 is for 480/580 8Gb cards.
For 470/570/480/580 4Gb cards use RI = 112
For 270X 4Gb best is RI = 59-60.