[HN Gopher] DIMM vs. Udimm vs. Rdimm vs. Sodimm vs. Cudimm: What...
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       DIMM vs. Udimm vs. Rdimm vs. Sodimm vs. Cudimm: What's the
       Difference?
        
       Author : trelane
       Score  : 47 points
       Date   : 2024-11-17 05:31 UTC (17 hours ago)
        
 (HTM) web link (www.corsair.com)
 (TXT) w3m dump (www.corsair.com)
        
       | Culonavirus wrote:
       | Yeah, but what about CAMM2? I need MORE ACRONYMS!! ;)
        
       | kvemkon wrote:
       | Related:
       | 
       | The Difference Between a Standard DIMM and a Cudimm or Csodimm
       | [Crucial/Micron] (16.11.2024)
       | 
       | https://news.ycombinator.com/item?id=42102076
        
       | ComputerGuru wrote:
       | This isn't really a deep dive into the tech, it's just an SEO
       | placeholder for a company that sells memory modules.
       | 
       | That aside, people usually learn about RDIMM the hard way when
       | they need to get ECC unbuffered RAM for something like
       | HEDT/workstation or tower server Xeon/i3/Ryzen with ECC support
       | but buy the cheaper RDIMM instead of the ECC UDIMM modules only
       | to figure out they don't work!
        
         | throwaway48476 wrote:
         | HEDT has disappeared. It's just server platforms with RDIMM
         | now.
        
           | buildbot wrote:
           | Not true, the W790 chipset is purely for HEDT/workstations,
           | distinct from the sapphire rapids server line. AMD also has
           | an entire separate HEDT socket, sTR5 for threadripper CPUs.
           | HEDT is alive and well!
        
             | wtallis wrote:
             | HEDT as a consumer product segment distinct from the
             | workstation segment is pretty close to dead. Intel hasn't
             | introduced a new HEDT socket since 2017 and hasn't launched
             | any new CPUs for that platform since 2019.
             | 
             | AMD's Threadripper line has been inconsistent; the 5000
             | series was all Threadripper PRO parts, then last year's
             | 7000 series brought back the non-PRO Threadripper options.
             | But even the entry-level Threadripper CPUs and TRX50
             | motherboards available today are less affordable than HEDT
             | systems were eg. 15 years ago. The high core counts
             | available in mainstream desktop sockets have shifted the
             | boundary between that segment and HEDT, and as a result
             | there aren't good options to step up to a platform with
             | more IO capability _without_ also stepping up to really
             | high CPU core counts.
        
       | dusted wrote:
       | it just dawned on me how trivially simple it would be for memory
       | controllers to implement ECC in UDIMMs, for every N words,
       | reserve 1 word for parity. You gain ECC for a small decrease in
       | capacity. Since the memory controller is on the CPU, it can
       | easily abstract this away.
        
         | kvemkon wrote:
         | Indeed. Intel has recently implemented it in a low-cost CPU
         | SoC: "in-band ECC".
         | 
         | https://news.ycombinator.com/item?id=41090956
         | 
         | But you not only loose some capacity. Some bandwidth is also
         | lost. And perhaps even some CPU cycles, since likely in-band
         | ECC hasn't been implemented purely in a hard IP-block.
        
           | wtallis wrote:
           | I think the bigger performance problem is that a read burst
           | from one channel of RAM is no longer matched to the CPU cache
           | line size when doing in-band ECC.
        
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       (page generated 2024-11-17 23:01 UTC)