Why the value of LowTotal is different in /proc/meminfo on two identical servers ?

Issue

• Why the value of LowTotal is different in /proc/meminfo on two identical servers with same hardware, BIOS and kernel version ?

Details from server: 1

# uname -r
2.6.18-348.12.1.el5PAE

# dmidecode | grep -A 3 "BIOS Information" 
BIOS Information
    Vendor: HP
    Version: P64
    Release Date: 05/05/2011

$ egrep -i "low|high" /proc/meminfo 
HighTotal:    24238204 kB
HighFree:     15364932 kB
LowTotal:       579608 kB   <<<<
LowFree:        215632 kB

Details from server: 2

# uname -r
2.6.18-348.12.1.el5PAE

# dmidecode | grep -A 3 "BIOS Information"
BIOS Information
        Vendor: HP
        Version: P64
        Release Date: 05/05/2011

# egrep -i "low|high" /proc/meminfo
HighTotal:    24238204 kB
HighFree:      9440544 kB
LowTotal:       710680 kB   <<<<
LowFree:        558924 kB