3 ms·

ECC is more costly in terms of the BoM and higher power consumption.

adrian_b 3y ago
The power consumption is higher by an amount that is not easily detectable. The power consumed by the relatively few gates that generate and verify the ECC code is dwarfed by the power consumption needed to transport bits over the PCB traces. The extra memory cell arrays for ECC bits add some power consumption for refreshing their content and the extra PCB traces for the ECC bits add some power consumption, but this extra power is in the milliwatt range, so it is negligible in comparison with the CPU and GPU power even in a small laptop, not only in a desktop. Most gaming desktops use overclocked memory modules that have an extra power consumption many times greater than the DDR5-4800 or DDR5-5600 ECC UDIMMs. The ECC UDIMMs never need heatsinks, while many of the commonly used overclocked DIMMs will overheat without heatsinks. So the claim that using ECC will increase the power consumption is completely bogus. Something like using a power-save profile instead of a high-performance profile, for clock management, or using JEDEC timings for memory, instead of high-performance timings, would diminish the power consumption by orders of magnitude more than not using ECC memory.
- frognumber 3y ago
  It's actually a bit more bogus than that. If I can tolerate occasional bit errors -- which ECC permits -- I can reduce my power consumption by far more than the overhead of ECC. Right now, I power rails set to where billions of bits to never flip. If I can tolerate a one-in-a-billion bit flip, my tolerances go up a lot, and power consumption goes down by a similar factor. Properly implemented, ECC would likely cut power while increasing reliability. "Properly implemented" only happens in volume. That sort of optimization makes no sense for the very limited volumes ECC has today. Neither do a lot of other optimizations.
  - thfuran 3y ago
    ECC is ubiquitous in the server space and I wouldn’t really classify that as limited volumes.
    - frognumber 3y ago
      Good point. Still, those sorts of tweaks are more important for battery-powered devices. I'm not sure the impact on server power consumption would be important. RAM is not power-hungry relative to a Xeon or an H100.
- eptcyka 3y ago
  Fair point, thanks for proving my naive assumptions wrong.

The power consumption is higher by an amount that is not easily detectable. The power consumed by the relatively few gates that generate and verify the ECC code is dwarfed by the power consumption needed to transport bits over the PCB traces. The extra memory cell arrays for ECC bits add some power consumption for refreshing their content and the extra PCB traces for the ECC bits add some power consumption, but this extra power is in the milliwatt range, so it is negligible in comparison with the CPU and GPU power even in a small laptop, not only in a desktop. Most gaming desktops use overclocked memory modules that have an extra power consumption many times greater than the DDR5-4800 or DDR5-5600 ECC UDIMMs. The ECC UDIMMs never need heatsinks, while many of the commonly used overclocked DIMMs will overheat without heatsinks. So the claim that using ECC will increase the power consumption is completely bogus. Something like using a power-save profile instead of a high-performance profile, for clock management, or using JEDEC timings for memory, instead of high-performance timings, would diminish the power consumption by orders of magnitude more than not using ECC memory.

frognumber 3y ago
It's actually a bit more bogus than that. If I can tolerate occasional bit errors -- which ECC permits -- I can reduce my power consumption by far more than the overhead of ECC. Right now, I power rails set to where billions of bits to never flip. If I can tolerate a one-in-a-billion bit flip, my tolerances go up a lot, and power consumption goes down by a similar factor. Properly implemented, ECC would likely cut power while increasing reliability. "Properly implemented" only happens in volume. That sort of optimization makes no sense for the very limited volumes ECC has today. Neither do a lot of other optimizations.
- thfuran 3y ago
  ECC is ubiquitous in the server space and I wouldn’t really classify that as limited volumes.
  - frognumber 3y ago
    Good point. Still, those sorts of tweaks are more important for battery-powered devices. I'm not sure the impact on server power consumption would be important. RAM is not power-hungry relative to a Xeon or an H100.
eptcyka 3y ago
Fair point, thanks for proving my naive assumptions wrong.