In order to start troubleshooting, please provide what graphics drivers and OS you are using (down to the build version, if possible), along with what you are using to test the cards with. It's much too difficult to come to anything conclusive when these types of things are left out...
Also keep in mind that unless you're testing 1:1 equipment under the exact conditions that your own results are most likely always going to vary and be different. Third party testers such as these typically give you an overview of their hardware but do not publish every single detail of their test machine. No two setups are absolutely identical, and you'll likely need to have some more advanced knowledge of system internals in order to achieve similar performance numbers.
i have rx vega 64 stirx crossfire setup whit ryzen 2700x croshair vi hero mobo and so on. after i look results on internet and compare to mine test i see that my results are like 30-40% lower. i have 1000w corsair psu, crossfire profile is enable and so on. any idea? thanks for help 
