Speed Vs. Latency

    Open question for you guys, I understand the difference between latency and speed, I think. My question is, during the analysis of cost vs. performance, where performance is key, such as the case with APU's, what is more vital, CAS or speed? or a better question is, how fast does RAM have to be in order for it to cancel a high latency out?  IE, is 2133MHz with a CAS of 9 faster in real world tests than 2400 or 2600 (overcloked for 2600) faster than 2400 or 2600 with a CAS of 11?  From what I have seen, these two RAM chip types are roughly the same in cost. 2133/9 is about the same cost as 2400/11.  So,  in my 6800k, Will they perform roughly the same?


ProSonic Live

PS. no, My screen name is not a Sonic the Hedgehog reference.

For an APU, clock speed is generally more beneficial than timings and latencies. That said, 2600 MHz may have slower timings in other areas (RAS delay, row precharge time, row active time) than 2400 MHz which may hinder performance slightly. Ultimately it depends on the quality of the kit you use.

Will performance may vary a lot depending on what software that are in use.

APU, are very memory-hungry and will generally perform better with higher frequency, where something like gaming might not require the huge memory-output but instead require faster response. Rendering generally also is depending on frequency and not affected by latency, as you are pulling huge memory-trucks that needs to be compress or whatnot.


See it like this: Higher frequency can be a truck delivering items for a store. The bigger the more it can transfer. For something you might not need the biggest truck, where it would be better having a single car as it can be there faster, but not having the inventory of a truck.


I normally recommend for gaming with a CPU + dGPU, a pair of 4GB with a frequency on 1600/1866 with a cas latency on 9. Get the cheapest you can find, there wont be a difference from branding to branding.


Whereof gaming with APUs you would also need to feed the IGP, which is very memory-hungry, there I would get a pair of 4GB with a frequency on 2133 or 2400MHz with a cas latency on 10-11. Again find the cheapest pair.