Hi Chris,
if the servers do not have a hardware agent running (e.g. HP Insight Agent) you could search for sysOID. The default snmp agent on typical Linux systems is net-snmp, which has unique OID per platform (1.3.6.1.4.1.8072.3.2.10 on x86).
You might also look for systemDescription which even could reveal more details about the Linux flavour being used (e.g.: " Linux hostname.domain.com 2.6.18-371.3.1.el5 #1 SMP Thu Dec 5 12:47:02 EST 2013 x86_64").
To optimize the searches, you should look for different attributes providing the same information but having different SSdb flags (memory, database, external).
regards,
Raphael