News Crucial's DDR5 RAM Is Ready For Retail

Ehhh, why is DDR5-4800 CAS 40 when DDR4-4800 is CAS 19?
That's going to negate all (or more) of the various other architectural performance improvements of DDR5.
While I don't have an exact answer, we can speculate:
  • DDR4-4800 isn't part of the JEDEC spec.
  • At least on Ryzen systems, memory controllers can't clock that fast anyway, so there's additional latency due to addressing memory at less than 1:1 clock speeds. If AMD's slide deck was any indication, DDR4-4400 CL18's latency isn't any better than DDR4-3200 CL14 when put into practice.
  • The absolute latency isn't that much better or worse than the JEDEC standard for DDR4 in its entirety
  • Assuming the table on Wikipedia is listing the official JEDEC standards for DDR4, it's likely JEDEC is being generous with timings and we'll likely see memory with faster timings becoming more mainstream
WTF, why is there a double height PCB for only 8 DRAM packages?

Why are you wasting so much PCB when you could've easily packaged it on smaller PCB?
Probably logistics. It's easier to mass produce one item than two.
 
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SethNW

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As with all new DDR generations, DDR5 will likely be downgrade in terms of everyday use and gaming, since when you combine frequency and amount of cycles in latency, it's response time in ns, is longer than DDR4. But it will be better for workloads that only care about bandwidth. So I won't be rushing to upgrade. Just as with DDR3, DDR4 will probably be fine for a while, till performance of DDR5 gets improved and software more optimized for it.
 

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