Some time ago, I bought a Celsius J550 workstation with an i7-6700. I wanted to upgrade it to its former glory with a Xeon, ECC RAM, and Quadro GPU. So I went on eBay, bought a Xeon E5-1270 v5 and 32GB ECC memory. I had a spare Quadro P2000 laying around, so I installed it as well. When I turned the machine on, it started beeping angrily at me.
Yeah, I had bought the wrong ECC memory.
Since the Celsius J550 is an entry-level workstation, it needs UDIMMs. I had bought RDIMMs, which are meant for high-end workstations and servers.
Let me elaborate a little bit on the differences.
RDIMM (Registered DIMM)
- Has a register between the DRAM chips and the system’s memory controller
- This register reduces the electrical load on the memory controller, allowing for higher memory capacities and potentially higher speeds
- Generally used in servers and high-end workstations
UDIMM (Unregistered DIMM)
- Also known as unbuffered DIMM
- Doesn’t have the extra register found in RDIMMs
- Typically less expensive and has slightly lower latency than RDIMMs
- Often used in desktop computers and less demanding server applications
LRDIMM (Load-Reduced DIMM)
- Similar to RDIMM but with additional buffering for even higher capacities
- Never personally experienced them, so I don’t know much about them
If you’re buying a regular full-fat workstation like the Lenovo ThinkStation P5x0, P7x0, or Dell Precision T7xxx, they definitely need RDIMMs.
Entry-level workstations usually need UDIMMs. These are basically platforms that accept normal CPUs like i5, i7 but also support Xeons. Examples include Dell Optiplex or Fujitsu Celsius desktop computers.
The same goes for motherboards. I have a Gigabyte MC12-LE0, which is a quite cheap motherboard with Ryzen and ECC support, and it also needs UDIMMs.
This post wouldn’t exist if companies provided better manuals and I had read them carefully enough 😃