А какая разница, если сервер поддерживает всего лишь один тип памяти?
В зависимости от модели - это или RDIMM или UDIMM.
UPD ответ не совсем однозначный, в виде сравнения отдельных модулей медленнее, если нескольких, то быстрее.
Based on guidance from Intel and internal testing, RDIMMs have better bandwidth when using more than one DIMM per memory channel (recall that Nehalem has up to 3 memory channels per socket). But, based on results from Intel, for a single DIMM per channel, UDIMMs produce approximately 0.5% better memory bandwidth than RDIMMs for the same processor frequency and memory frequency (and rank). For two DIMMs per channel, RDIMMs are about 8.7% faster than UDIMMs.
en.community.dell.com/techcenter/b/techcenter/arch...