Jump to content
Search In
  • More options...
Find results that contain...
Find results in...
NDRE

What’s the differency between memory real latency 12ns vs 11.25ns?

Recommended Posts

Posted · Original PosterOP

Hello! 

I’m curious about the perceived difference between these 2 memory kits: 

 

1. DDR4-2666 CL16-18-18 @1.2V (real latency: 12ns)

 

2. DDR4-3200 CL18-21-21 @1.2V (real latency: 11.25ns) 

 

The 2nd kit has a speed advantage of -0.75ns (6.25%) over the 1st kit. 

 

QUESTION: 

6.25% speed advantage translates to how much overall, in tests? 

(4%? 2%? 1%?)

Link to post
Share on other sites

Assuming my math is correct, in order there to be an accumulation of one second lost using the slower RAM, you're looking at 1,333,333,333 requests. Assuming a worst case scenario of requesting only 4 KiB pages, this is about 5TB of data.

 

Basically, you're looking at almost zilch with regards to speed advantage.

Link to post
Share on other sites
Posted · Original PosterOP
10 hours ago, Mira Yurizaki said:

Assuming my math is correct, in order there to be an accumulation of one second lost using the slower RAM, you're looking at 1,333,333,333 requests. Assuming a worst case scenario of requesting only 4 KiB pages, this is about 5TB of data.

 

Basically, you're looking at almost zilch with regards to speed advantage.

I’m afraid that your answer ain’t clear enough for me. 

Can you, please, be more specific?

Link to post
Share on other sites

depends.

on the uArch and what workload you are using. for example, if you are using a memory bandwidth heavy application (i.e. idk AIDA64 disk and cache benchmark), it might make a 1-3% difference, might be more on ryzen 1st/2nd gen, less on intel. the bandwidth is major difference. The only time you should start to tighten timings is after you get to the highest possible frequency (with loosening timings, 4600mhz CL24 is better than 3200mhz CL16) or 3733mhz on ryzen 3rd gen.

subtimings don't really help much, even on memory and cache benchmarks.


Hello! Feel free to PM me anything. Here's my stuff below!

PC (Main)

Spoiler

CPU: i5-8400 CPU Cooler: Cryorig M9 Plus   Motherboard: Gigabyte B360M DS3H | RAM: Crucial Ballistix Sport 2x8 DDR4-2400 SSD: Inland 480GB SSD | Video Card: RX 570 4GB Strix OC | Case: Fractal Design Meshify C White TGPSU: EVGA SuperNOVA G3 750 Monitor: Sceptre 24" 1080p 75hz Webcam: Logitech C920 Keyboard: Modded FC660M | Mouse: G305

 

NAS:

Spoiler

Synology DS418J w/ 4x WD Red Pro 6TB RAID 10

Seagate 5TB external SMR 2.5" HDD

MS Office 365 - 1TB Onedrive

 

Phone/Tablet:

Spoiler

iPhone XR 64GB iPad Mini 4 128GB

 

Laptops:

Spoiler

Dell XPS 15 9570 i7-8750H + 1050 Ti MacBook Air 13" mid-2012

 

Audio:

Spoiler

 Audio-Technica AD700X + Modmic 4 KZ ZS10 Pro | Audio-Technica LP120USB Audioengine A2+

 

Link to post
Share on other sites
Posted · Original PosterOP
10 hours ago, Mira Yurizaki said:

What about my answer isn't clear?

I was asking for percentages in benchmarks. 

(I’m on Intel platform).

Link to post
Share on other sites
Posted · Original PosterOP
10 hours ago, GoldenLag said:

it depends. 

I’m on Intel platform. 

I’m interested into knowing the speed differences, in percentages, in benchmarks. 

Link to post
Share on other sites
1 minute ago, NDRE said:

I was asking for percentages in benchmarks. 

(I’m on Intel platform).

It depends on what test they're doing and how long it's being done. If it's a bandwidth test, there's no advantage for using low latency RAM. If it's a "how fast can this RAM service requests", if it's only doing something like 1000 requests, the delay is 750ns on the higher latency RAM, assuming no other factors are involved. This is imperceptible as far as human timescales are concerned.

 

But if you want a stupid simple answer:

  • Raw bandwidth test: there's no advantage
  • Servicing requests tests: as high as 6.25% better for the lower latency RAM.
Link to post
Share on other sites
Posted · Original PosterOP
11 hours ago, Mira Yurizaki said:

It depends on what test they're doing and how long it's being done. If it's a bandwidth test, there's no advantage for using low latency RAM. If it's a "how fast can this RAM service requests", if it's only doing something like 1000 requests, the delay is 750ns on the higher latency RAM, assuming no other factors are involved. This is imperceptible as far as human timescales are concerned.

 

But if you want a stupid simple answer:

  • Raw bandwidth test: there's no advantage
  • Servicing requests tests: as high as 6.25% better for the lower latency RAM.

OK. I think I get it! 

With other words there’s no perceptible advantage to move to the higher MT/s kit...

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


×