3 ms·

I do not believe they were asking for CAMM as replacement for soldered RAM, but as an upgrade for DIMMs in desktop. CAMM is touted as being better than DIMMs w

I do not believe they were asking for CAMM as replacement for soldered RAM, but as an upgrade for DIMMs in desktop. CAMM is touted as being better than DIMMs when it comes to signal integrity and possible speed. Soldered of course beat any socket, in-package beats any soldered RAM, and on-die beat any external component. That AMD Strix Halo is unable to maintain signal integrity for any socketed RAM is a Strix Halo problem, not a socket problem. They probably backed themselves a bit into a corner with other parts of the design sacrifying tolerances on the memory side, and it's a lot easier to push motherboard design requirements than redoing a chip. If this wasn't a Strix Halo issue, then they would have been able to run with socketed memory with a lower memory clock. All CPUs, this one included, has variable memory clocks that could be utilized and perform memory training as even the PCB traces to the chip cause significant signal degradation.

kimixa 2y ago
For signal integrity issues increasing the link power can often overcome some of the issues caused by longer traces and connectors in the line - while less of an issue for desktop devices, then that goes against the ideal of a low-powered device with limited cooling. Doubly so as it's hard to re-clock in the timescales needed for intermittent use power saving, so will be using that extra power when idle. I suspect the earlier comment about "Half the performance with CAMM" is likely at iso-power, but that might still be a pretty big dealbreaker.
- arghwhat 2y ago
  More power is to overcome switching losses and parasitic reactances. You can increase drive strength up to a limit to overcome this, but a slight clock reduction will make things work at the same power. CPU's and GPU's reclock extremely fast to my knowledge, but what we're talking about isn't dynamic reclocking, just limiting the max clock as suitable to the system design. We already see this when we have laptop silicon that run faster clocks when using soldered RAM compared to when the same silicon is using socketed counterparts. That this wasn't an option probably mean that they're either far too close to the limit, or unwilling to allow a design that runs below max speed.

kimixa 2y ago

For signal integrity issues increasing the link power can often overcome some of the issues caused by longer traces and connectors in the line - while less of an issue for desktop devices, then that goes against the ideal of a low-powered device with limited cooling. Doubly so as it's hard to re-clock in the timescales needed for intermittent use power saving, so will be using that extra power when idle. I suspect the earlier comment about "Half the performance with CAMM" is likely at iso-power, but that might still be a pretty big dealbreaker.

arghwhat 2y ago
More power is to overcome switching losses and parasitic reactances. You can increase drive strength up to a limit to overcome this, but a slight clock reduction will make things work at the same power. CPU's and GPU's reclock extremely fast to my knowledge, but what we're talking about isn't dynamic reclocking, just limiting the max clock as suitable to the system design. We already see this when we have laptop silicon that run faster clocks when using soldered RAM compared to when the same silicon is using socketed counterparts. That this wasn't an option probably mean that they're either far too close to the limit, or unwilling to allow a design that runs below max speed.