Raid 0 Speed different from two server same SSD and part configuration ?

[liamhoang14]

I have 2 dl360p gen8 the HP server. Both units are running same configuration of the ram, cpu, hard drive, ssd and windows.
Both use p420i raid and same configuration

Server 1: I put ssd to slot 1 2 3 4 

Server 2: I put ssd to slot 2 4 6 7 ( newer firmware bios )

But the speed test for hard drive from server 2 always faster x2 than the server 1. 

Hard drive arrangement affect speed or it's from BIOS firmware?