Review on Crucial Ballistix Sport LT 2400MHz DDR4 Laptop Gaming Memory 8GB Single Module CL16 BLS8G4S240FSD (Gray) by Joseph Long

Almost everyone knows the advantages of dual-channel RAM, but not dual-rank. What is dual rank? I'll keep it simple - it's like bidirectional multithreading for RAM. Having the memory chips on a channel grouped into 2 groups (as opposed to 1 group for peer-to-peer) allows 2 sets of commands to be issued consecutively without delay for each group of chips. Why is this an advantage? Good, because memory spends multiple cycles fetching the requested addresses (ie, memory timings of 16-16-16-39 mean it takes at least 16 cycles to select a location in the memory array). So instead of sitting around doing nothing for 16 cycles after issuing a RAM command, you can issue a completely different command to the second group of chips on the RAM module. If you want the highest memory bandwidth, you should use as many channels and ranks as possible. Dual channel + dual rank memory offers 15-20% higher memory bandwidth compared to dual channel + single rank memory, all other things being equal. While all 16GB modules are almost certainly dual-ranked, they are also much more expensive. The vast majority of 8GB DDR4 modules are peer-to-peer modules. If you don't need 32GB of total RAM, these 8GB modules offer the cheapest alternative to 16GB of total RAM. I replaced the factory 2400 17-17-17s with these 2400 16-16-16s on my XPS 15 9560 and increased the memory bandwidth by 5 GB/s. By the way, the 2666 model has timings of 16-18-18-38-61 at 2666 and timings of 16-16-16-39-55 at 2400. Your bios will automatically choose the maximum supported clock speed up to 2400 or you can try it to force yourself through the BIOS. 2666 requires XMP 2.0 profile support, but you can manually set the appropriate timings if your system supports it. One thing to be aware of is that dual-ranked memory puts extra stress on the memory bus, and if you're aiming for the highest memory clocks (e.g. performance will be increased by a board with higher RAM clock speeds), you should get involved Satisfy peer-to-peer as dual-rank may not have as high clock speeds depending on hardware/BIOS. Otherwise, there is no point in aiming for higher RAM clock speeds, and you should instead aim for the shortest instruction cycle (memory timing * 1/clock, where actual DDR4 memory frequency is 1/2 that specified, e.g. 16 CAS * 1 /( 2400/2) = cycle time 13.333 ns). I'd also like to point out that there is a slight increase in latency with dual rank, but if you're concerned about latency, consider CPU cache latency instead. I should also mention that due to the CPU cache, most normal CPU bound applications will not see the benefits of dual rank RAM. However, if you are using an iGPU along with a CPU, Dual Rank's 15-20% advantage in memory bandwidth will most likely result in a 15-20% performance boost in 3D/computing applications using the iGPU. So you got it.