DCS: Disk Performance Data

So the other night after working on the putting the thermal pads on my NVMe, I took a look at some of the performance data while running DCS, just to see what was really being used. For reference, here are my graphics settings, which will give an idea of the demand on the system. I’ve covered where SSDs improved DCS in my build before, but here are some as-we-play numbers.

Flight:
Hollo Pointe North, running Offensive Posture (Caucasus), F/A-18 to fly CAP.

Mission Load -> Idle Ready to Taxi:
Data read from DCS-only NVMe SSD: 9 Gigabytes.

In-Flight + Camera Work Test 1:

  • Cockpit View
  • F2 Camera, of own aircraft
  • Shift+F11 Free Camera, moving at 56,500kn around entire map

Data read speeds: approximately 20MB/s to 150MB/s (when needed)

Interesting to note with this is that a typical desktop hard drive (using some numbers from WD’s spec sheets and user benchmarks) would have a peak sequential transfer speed of 150-200MB/s. Sequential implies a single, large, defragmented file. Reading of many smaller files, like what DCS would have to do for various textures would be substantially slower, potentially even less than half the max sequential read. Citing numbers for random reads really depends upon quantity, size and fragmentation of the files.

In-Flight + Camera Work Test 2:

  • F2 Camera, viewing all aircraft mission will allow to cycle through
  • F11 Airfield camera, all airfields cycled

Peak read speed: 333MB/s.
Total data read: 13GB.

Other System Resource Status:

  • 21.9GB of RAM
  • VRAM ~7 out of 8GB

Other numbers of interest:

**Speeds are give as maximum sequential speeds, random speeds are measured in IOPs.

3 Likes

Interesting data thanks. I must check my 970 Evo for comparison. Your figures also blow out the water the myth dcs never uses more than 16Gb ram

That myth I think is rooted in the fact that when you have 16GB of RAM, you don’t see it all get used.

For example, when I had 16GB on my old build, I typically was only using 11-13GB. With a few gigs still free, it would seem DCS isn’t going to use it. Primarily I think it just pushes more to the pagefile, if that’s available.

Same as how your graphics card typically won’t use all its VRAM, mine doesn’t like to go over 7.9 out of 8GB - but I am sure if I got a 2080ti with 11GB of VRAM I’d see it use 10.9 instead.

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Hi Wes,

So what I’m hearing is: DCS will take advantage of 32GB of RAM if you have it installed. I’ve been on the fence regarding adding more RAM because of the idea that 32GB is overkill. I’m planning a future build just for simming and VR. Thoughts?

Thanks,

3 Likes

When I bought my DDR4 RAM in January, I bought two 16GB kits (2x 8GB), each kit was $189.99 - that was nearly $400 in RAM (Canadian Dollars, I should add).

For anyone that wants evidence, here’s my receipt:

Those same kits today are $99.99 at Canada Computers (where I bought) on sale (reg. $124.99)
https://www.canadacomputers.com/product_info.php?cPath=24_311_1326&item_id=122566

For you Americans, it’s $95.99USD at Newegg US.

RAM is relatively cheap now, and you won’t lose anything other than a few hundred bucks with a large potential gain and future proofing of your computer, which may keep the build viable a few extra years before you rebuild.

You graphics settings may not take you above 16GB once you have 32GB but you may hit say 15GB. The way DCS seems to work with Windows, if you only had 16 installed it won’t use more than say 12.

Perhaps a year ago, it wasn’t worth the expense - but now it’s worth it I would say.

———

Mistakes I made:

Check your motherboard’s QVL list for RAM, and buy a kit off the list. Also, most boards won’t QVL a double-kit setup like mine, so buy a kit that’s say 4x8GB sticks instead of what I did with two kits of 2x8GB. (My ram is not on QVL for my board)

QVL listed RAM is your best bet to run XMP (NOT a guarantee!!) which is how you get to 3200Mhz (using my RAM as an example). Motherboards vary on the base clock they support - mine is 2133mhz, which is how fast my RAM runs since I don’t use XMP profiles. XMP is technically an overclock, and may not be stable.

If you don’t want to use XMP, you can save money by buying lower speed RAM to match your motherboard, so in my case I could have bought 2133Mhz RAM and saved a few bucks.

My previous PC was also a mix of kits as I had a RAM stick die, so mixing won’t kill you either if you already have 2x8GB, and buy another pack.

2 Likes

cool

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