Memory timings

[PravusJSB]

Hi, I have messed around with settings and setup a lot over the years trying to get the best VR experience and one thing that I did do which made a huge difference is memory overclocking, more specifically I sacrificed speed for tight timings. I have not seen anyone ever talk about timings and I always wanted to write something but I appreciate that this type of overclock is not for the feint of heart. I wondered if anyone else had seen similar results or has the skill and inclination to give it a go and confirm it is indeed a great way to boost performance. 
 

i managed to get my timings to 13-15-15-28 @3000 (32Gb) and importantly a 1T command rate. 

[dburne]

Mine at XMP profile are 14-14-14 3200 MHz. 2T

[edmuss]

My xmp is 3200 16-18-18-38 1T, I've tried reducing the frequency in order to tighten the timings but the best I can get it to is 2866 14-16-16-35 1T with initial stability testing through Ryzen master but not had chance to test in DCS yet.

There is a small reduction in the latency from 10ns to around 9.6ns but I'm not too sure if that'll make any significant difference. I can put my hands on a 32gb kit (borrowed from work) that is 3600 16-18-18 which at xmp is 8.8ns with potential to tighten timings on top.

@PravusJSB In your experience what gains the performance uplift in DCS vr? Is it CPU timing only or does the GPU benefit as well? I remember that I gained an extra 25%+ improvement in arma3 simply by switching ddr3 1600 to ddr3 2133, similar software with limited multi core support on the CPU.

[PravusJSB]

@edmuss That sir is a complex topic and I have a lot of information about it, and it's very frame of reference dependant. In general and overclocking aside I'd say ensure you have no hardware bottlenecks and dont be greedy with settings. A common mistake I see people make is with a bottleneck to the GPU, which can be seen with low GPU utilisation, people lower their settings and it gets worse. Instead try to understand the bottleneck and mitigate it and normally upping a GPU related settings much much higher can ease or fix the issue, as it slows the GPU down and brings it back inline with the CPU.

I saw a big improvement each step i got the core latency down and stable.

For reference i get zero stutters, zero tiny spikes, butter smooth, Syria, RiftS, visual fidelity high.

[edmuss]

Thanks for the insight, I'm not sure that I'm specifically bottlenecked per se. GPU utilisation is 90%+ (when smoothing is off) and CPU frametimes are nominally 9-16ish ms. I don't tend to suffer from any stuttering apart from an occasional a miniscule hitch as smoothing turns on and off.

Whilst the CPU isn't all singing and dancing it seems to be holding its own, I guess the faster ram timings would help more on heavier AI missions. I maximise GPU settings so it's on its knees as much as possible.

I think I'll borrow the kit and see if it makes any noticeable difference. With arma3 it was massively CPU bound but that was at 1080p so nowhere near the GPU loads imparted by VR.

[edmuss]

Well I've borrowed the kit of 3600 and at stock timings I don't see any real GPU frametime reduction (but I wasn't expecting any as the 3070 is pretty much saturated with my settings) but I think the CPU times have dropped by 2-3ms in places.  I haven't done any direct back to back testing with the lower ram speed but the chart certainly seemed lower and there seemed to be far less jumps/spikes on the CPU trace.  The GPU frametimes seemed to be more stable as well, the transition from smoothing on/off also seemed to be smoother.

Lots of seemed to be and I think going on up there!  Could all be placebo...

This ballistix kit appears to be B-die so should be quite a good overclocker, I've never clocked ram before though so no idea where I should be going

[PravusJSB]

Thats positive, thanks for testing. Yea 2 units of data isnt enough to go on, but it does seem like the timings might be a thing.

I'm on much older hardware, 6700K@4.6 2080S so every little helps for me.

Edited March 11, 2022 by PravusJSB

[edmuss]

Yeah and my unit of data is seat of the pants, feels smoother without any corroborating evidence

I don't think that it's a magic bullet but perhaps can release some additional CPU capacity as part of a series of incremental gains.

[PravusJSB]

but like you said, if you had no bottleneck then the gains will be small, for me it was vastly different.