Summary of a video about Intel 12th gen's memory system and performance

[Jurrunio]

Source: 板廠沒有說的秘密 TOPPC, the presenter is employed by MSI, presented in Chinese (Mandarin)

 

Summary:

Rocket Lake S (11th gen) to Alder Lake S (12th gen): single IMC and DDR4 only to dual IMC and both DDR4 & DDR5, increases bandwidth but also increases latency

 

DDR5: x8 and x16 dies both available in at least entry level frequencies (4800MHz), not sure about higher frequencies like 5600MHz or 6400MHz. x16 is quite a bit worse than x8 in latency but is also (supposedly anyway) cheaper. 

If you're low on budget to buy something that's guaranteed x8 DDR5, might as well get x8 DDR4 (note: at least 2933MHz, x16 is possible at lower frequency).

 

Combined difference between x8 DDR4 and x16 DDR5 on ADL-S combines to about 15% worse bandwidth and 30% greater latency for x16 DDR5 at the same frequency and CAS latency. If you have x8 DDR5, difference shrinks to negligible for bandwidth and 20% greater latency. Ofc DDR4 that can match DDR5 in frequency will be expensive, but DDR4 does make sense, especially those with tigher timings, with Alder Lake S.

 

 

My opinion:

Whether DDR4 or DDR5 is better will be workload dependent, hopefully someone would make benchmarks about how different apps scale with bandwidth and latency.

 

Some extra math: Bandwidth and frequency are directly related, so 4000MHz and 4400MHz DDR4 will be equivalent to 4800MHz and 5200MHz x16 DDR5 in bandwidth but still offer latency benefits.

[Guest]

G.Skill Trident Z5 6666mhz is the fastest memory so far with 40-40-40-76 timings achieving 7000mhz on ambient. Samsung Dies.

 

It's always about bandwidth. That's why we overclock.....

[Jurrunio]

47 minutes ago, ShrimpBrime said:

It's always about bandwidth. That's why we overclock.....

If you overclock for benchmarks maybe. For games, latency is more important especially since games today are optimized for DDR4 platforms with way less bandwidth. That's fundamentally why we have DDR and GDDR in the first place, preference over latency or bandwidth.

[Guest]

21 minutes ago, Jurrunio said:

If you overclock for benchmarks maybe. For games, latency is more important especially since games today are optimized for DDR4 platforms with way less bandwidth. That's fundamentally why we have DDR and GDDR in the first place, preference over latency or bandwidth.

As DDR5 matures, I'm sure the overclockers will find ways to decrease latency at the higher bandwidths.

 

Ddr4? I just recently made a thread with sk hynix running 3800mhz CL22-24-24 with a 53ns measured average latency. 

 

So 7000mhz CL40 would be a comparable experience I'd imagine. But the DDR5 will just have gobs more bandwidth.