Decrease latency

I have three identical clusters using

mlx4_core: Mellanox ConnectX core driver v2.2-1 (Feb, 2014)

mlx4_en: Mellanox ConnectX HCA Ethernet driver v2.2-1 (Feb 2014)

<mlx4_ib> mlx4_ib_add: mlx4_ib: Mellanox ConnectX InfiniBand driver v2.2-1 (Feb 2014) 40G

My cards are single port

CA 'mlx4_0'

    CA type: MT4099

    Number of ports: 1

    Firmware version: 2.31.5050

    Hardware version: 0

    Node GUID: 0xf45214030057a450

    System image GUID: 0xf45214030057a453

    Port 1:

        State: Active

        Physical state: LinkUp

        Rate: 40

        Base lid: 3

        LMC: 0

        SM lid: 1

        Capability mask: 0x02514868

        Port GUID: 0xf45214030057a451

        Link layer: InfiniBand

Two of my systems give me an average of .17ms latency. The third system is .38ms. There is no load on any of the systems when I am running the ibping test. Does anyone have an idea on what may be causing this or a suggestion on where/what to look at?

Thanks,

Dave