HP Manufacture memory for specific products, the motherboards tend to be manufactured with that specification in mind, including DIMM Slots, where the slot to fix the DIMM in will be in different positions depending on the memory required, this difference will even be present between different models of desktop. This also prevents grey market / counterfeit memory being supplied.
Also if you look at HP Part Surfer for 501536-001 / 536890-001 you can see all the compatible products for each DIMM
Although the memory descriptions are similar and on paper they may look the same, they are manufactured for different functions and different products. I wouldn’t ever suggest purchasing server memory for a workstation.
R5 refers to CAS 5 and R9 to CAS 9 memory (The R is an HP thing but refers to CAS) – This refers to the timing or number of clock cycles it takes to perform an indicated function. Generally the lower the CAS number the faster the memory. All being equal though the main problem is still that the memory is developed specifically for the motherboard / Processor / Architecture of either the server or Workstation it is to work for and is not interchangeable between different product sets I’m afraid. The pin configuration, although exactly the same amount of pins, is different in the fact that the guide slot for fitting into the DIMM Slot on the motherboard is in a different place.
Last edited by Linux1000000; 09-08-2011 at 10:49 AM.