With
CPU - Z 1.19A you can get a more exact readout of your SPD like in the case of my XMS3500C2PT;
CPU-Z version 1.19a
Memory Modules Serial Presence Detect (SPD)
Module #0
Memory type DDR-SDRAM
Manufacturer (ID) Corsair (7F7F9E0000000000)
Size 256MBytes
Max bandwidth PC3200 (200MHz)
Part number CMX256A-3500C2
Max frequency @CAS#2.0 166MHz
Max frequency @CAS#2.5 200MHz
Module #1
Memory type DDR-SDRAM
Manufacturer (ID) Corsair (7F7F9E0000000000)
Size 256MBytes
Max bandwidth PC3200 (200MHz)
Part number CMX256A-3500C2
Max frequency @CAS#2.0 166MHz
Max frequency @CAS#2.5 200MHz
What this tells you in the case of XMS3200, on the XMS3500 its a whole different story because of JEDEC, is what Corsair has tested them to be stable & reliable within their specific guidelines of voltage & speed with their own specific tests.
Are you limited by this? Well that's up to experience & the willingness to void the warranty. What I can tell you is that my modules have gone past their "conservative" SPD timings & proven themselves to be awesome overclockers.
EDIT*