DDR4-2666 vs higher memory speeds for CPU matching.

[whm1974]

I've been playing around with putting together specs on pcpartpicker.com and quickly noticed the vast price differences with DDR4-2666 compared to much high rated DDR4 memory, especially with speeds over DDR4-3200. And I'm thinking that once past 3200 you will get diminishing returns as well.

Due to pricing I don't think it is worth it to use higher spec DIMMs then 2666 for APUs/CPUs such as the 2200G, 8100, and 8400.

So I'm thinking that DDR4-3000/3200 should be reserved for such processors like the 2400G, 2600, 2700, and 8700. And that memory past 3200 isn't worth getting.

Any thoughts on this?

 

[cmdrdredd]

SOme CPUs scale with the memory, meaning you get higher performance from programs when you pair the CPU with fast memory. I believe the new Ryzen CPUs really benefit from fast memory and show the biggest benefit.

 

[whm1974]

SOme CPUs scale with the memory, meaning you get higher performance from programs when you pair the CPU with fast memory. I believe the new Ryzen CPUs really benefit from fast memory and show the biggest benefit.

I've seen some of the memory benchmarks of the Ryzen 2000 series processors, but would you pair expensive fast memory with a budget processor such as the 2200G or 8100? To me it doen't make sense. Now that said I would get the current standard speed the processor supports, which right now is DDR-2666 and I wouldn't go below that.

 

[LTC8K6]

You aren't running the memory out of spec on a locked Intel chip unless you bought a Z chipset board for it, right?

 

[whm1974]

You aren't running the memory out of spec on a locked Intel chip unless you bought a Z chipset board for it, right?

I have a Z87 board and no I'm not running memory out of spec.

 

[LTC8K6]

I have a Z87 board and no I'm not running memory out of spec.

I wrote that badly.

You generally can't overclock the ram with Intel unless you have a Z board.

IOW, if you, for some reason, wanted to overclock the ram on a locked Intel chip, you'd have to pay for a Z board, otherwise you are stuck at stock ram speed.
For the i5-8400 that's 2666 and for the i3-8100 that's 2400.

 

[whm1974]

I wrote that badly.

You generally can't overclock the ram with Intel unless you have a Z board.

IOW, if you, for some reason, wanted to overclock the ram on a locked Intel chip, you'd have to pay for a Z board, otherwise you are stuck at stock ram speed.
For the i5-8400 that's 2666 and for the i3-8100 that's 2400.

Due to AMD's strong comeback with Ryzen, I am heavy considering building an AMD rig in a few years depending if they can keep this up.

 

[Dasa2]

When software overflows the cpu cache it moves to the next level l1 l2 l3 each time it gets bigger and slower and then you have the ram which you can think of as the l4 cache
Most games heavily overflow the cache or just need random data that it cant predict needs to be loaded into the l3 cache before hand and this is why ram speed improves the performance of any cpu but only with software that doesn't fit whats needed into the cache

When using igp the bandwidth requirements go up significantly while cpu are more sensitive to latency

i5 8400 with 3066 ram can be faster than i5 8600 using 2133 and not far behind it using 2666
https://www.eurogamer.net/articles/...-coffee-lake-s-core-i5-8400-i5-8600k-review_1

2200g with 3200 ram would not not far behind 2400g with 2400 ram
https://www.pcper.com/reviews/Graphics-Cards/AMD-Ryzen-5-2400G-Memory-Speed-Performance-Analysis
https://www.tomshardware.com/reviews/raven-ridge-memory-scaling-benchmarks,5489.html

I don't know about prices where you are but in au 2200g to 2400g price difference is a lot bigger than 2400\2666 to 3000\3200
With intel it gets a bit more messy as to go over 2666 you also need to spend extra for a z370 mb so it may not be worth it

 

[whm1974]

I don't know about prices where you are but in au 2200g to 2400g price difference is a lot bigger than 2400\2666 to 3000\3200
With intel it gets a bit more messy as to go over 2666 you also need to spend extra for a z370 mb so it may not be worth it

Yeah with the Ryzen APUs/CPUs I would pony up for 3000/3200 memory speeds since they can use it without having to buy an expensive motherboard.

 

[Organik]

Let me throw this in. What is more important Mhz or latency. You can buy a 3200Mhz kit that has 16cl then you downclock it to 2900Mhz and go to 12 or 13cl OR, you overclock it to 3500Mhz and change the CL to 17 ..... ?

 

[Batboy88]

The 7700k has been a BLAST with 3200mhz. It is still about the sweet spot and with Timings. Go up to 3600mhz Maybe...depends on the Board too might be some support problems with some faster stuff.

 

[Dasa2]

Let me throw this in. What is more important Mhz or latency. You can buy a 3200Mhz kit that has 16cl then you downclock it to 2900Mhz and go to 12 or 13cl OR, you overclock it to 3500Mhz and change the CL to 17 ..... ?

It's mostly about balance since increasing frequency also reduces latency provide timings don't go to shit
https://en.wikipedia.org/wiki/CAS_latency

Here is a quick and dirty calculation that is handy for a rough guideline
3000 divided by 15 = 200
3200 \ 16 = 200
So they both have a similar final latency but the 3200 kit will have a higher bandwidth and if used with Ryzen the higher frequency will also reduce the latency of the infinity fabric.
3600 \ 17 = 211 so this also has a tighter final latency than 3000c15 despite the slacker timings and a lot more bandwidth.

 

[Organik]

I would be happy with a 2666 @ 11cl. Rather a 3200 @ 16cl .. IMO the 2666 will blow the 3200 away if you OC the 2666 properly Also Im getting 59ns latency just FYI.

 

[Dasa2]

IMO the 2666 will blow the 3200 away if you OC the 2666 properly Also Im getting 59ns latency just FYI.

Not all 2666 is capable of c11 but yes 2666c11 would probably be faster than 3200c16 for CPU but 3200c16 would probably be faster for a APU.

Here is my 3200c14 kit at 3000c12 = 37.3ns vs 3866c16 = 36.3ns
Neither of these proved to be 24\7 Stable but the 3000c12 was by far the least stable.
I'm currently running 3733c16 T2 300tRFC

https://www.overclock.net/forum/180...0c11-2133c9-ddr4-2133c15-3000c12-4000c17.html

 

[Organik]

Good stuff, thanks for the post / pics. thx You have nice timings and overclock on RAM ,,, good work....

That is a sexy latency on the RAM,, very cool

 

[Organik]

The 7700k has been a BLAST with 3200mhz. It is still about the sweet spot and with Timings. Go up to 3600mhz Maybe...depends on the Board too might be some support problems with some faster stuff.

Yes like cheap VRM and what have you.

 

[Organik]

That is sick RAM you have such tight timings for such high Mhz. Wow is all I can say.

 

[Dasa2]

Most kits with samsung b die will hit that or better with a decent mb\memory controller
I think my 6700k is the main thing holding it back.

One of the best binned kits of B-die before the price blows way out would be 3600c15 $250 but 3200c14 at $200 is still the best value.

Dual channel results in a lower final latency than your quad channel setup but half the bandwidth.
The more ram you have the harder it is on the memory controller too, the fact that you have 64G quad channel RAM at 1900c9 impressive.
If you have 2666 ddr4 now I'm guessing you have a newer system?