Registered CT25672Y40B memory modules from Crucial Technology are built upon 256Mb 5ns DRAM devices from Micron Technology. The products are compliant with AMD Athlon 64 FX, AMD Opteron as well as Intel Xeon applications and sport error check (ECC). In order to provide rock-stable operation Crucial programs modules at a very conservative CL=3 timings.Though a computer system with 8GB memory is not going to be affordable for normal people, one of these 2GB ECC PC3200 modules from Crucial costs around $999.
32-bit processors, such as Intel Pentium 4 or AMD Athlon XP, cannot address more than 4GB of memory, an issue observers point out to be a disadvantage of systems powered by such chips. Intel Xeon CPUs can handle up to 64GB of memory, while 64-bit chips, such as Intel Itanium, AMD Opteron, AMD Athlon 64 and plethora of others, can address up to 1TB of RAM. Even though Athlon 64 CPUs have such internal advantage over Intel Pentium 4, systems based on AMD Athlon 64 available now can sport up to 3GB of memory only, whereas Intel Pentium 4-based PCs handle up to 4GB these days. Being based on server technology, AMD Athlon 64 FX computers are equipped with more DIMM slots and allow installation of up to 8GB of PC3200 memory, or 4 modules 2GB per each.
Source: X-Bit Labs