19 minutes ago, w6kd said:

If the choice is between 32GB of average RAM and 16GB of high-performance RAM, I'd go with the 16GB config.

Also, a lot of the conventional wisdom on RAM has its roots in CPUs and chipsets several generations old.  I don't think the oft-held notion that RAM speed doesn't make a difference still holds true with processor speeds now approaching the mid-5GHz range.  It just doesn't make sense to me that increasing CPU throughput 35-50% (speed and IPC) while using RAM running the same approximate latencies wouldn't waste that additional CPU throughput with alot of empty clock ticks spent waiting for data.

The real measure of RAM performance is true latency, roughly computed (in ns) as (2000 x CAS level)/Speed (MHz).  Lower is better.  RAM with true latency of ~10 ns is average consumer-grade stuff, 9-10 is good, and <9 is high performance.  As an example, 3000 MHz CAS 15 RAM has a true latency of 2000*15/3000 = 10 ns (average).  And supposedly faster 3600 MHz CAS 18 ram has a true latency of 2000*18/3600 = 10ns.  Yup, no faster at all, in fact if you take the heat spreader off, don't be surprised to find the same memory ICs on the DIMM.

The chip configuration can make a difference in how much load is placed on the CPU's IMC (integrated memory controller).  That's why, usually, 2 DIMMs are better than 4, although 2 double-sided DIMMs versus 4 single-sided might be close to the same.  Bottom line, there's more detail worth considering than just price and clock speed.  You can get better-grade stuff without hitting the pricey top end if you know what to look for.  And you can get stuck with low-performance skunky RAM dolled-up like a pig wearing lipstick if you're not asking the right questions.

Regards

 

Bob,

I appreciate you taking the time to write that but sadly deciding which RAM I should buy seems to require a degree in mathematics. Surely there must be a website somewhere where you choose the chipset of the mobo and select the processor and it shows you entry level, intermediate and top quality RAM.

The user then makes their choice with all the hard work done by the software. Does such a service exist? If not then with an Asus Prime Z370-A mobo and i7-8086K what are my best choices for middle to top end RAM. 16Gb now looking likely.

Quote

.....the more important aspect of P3D is to have MORE than 8GB VRAM if you want to bask in it's splendor …

Doesn't this depend on what resolution you are running at? I would have thought that 8GB VRAM would be more than enough for a single monitor @ 1920x1080 resolution.

1 minute ago, Christopher Low said:

Doesn't this depend on what resolution you are running at? I would have thought that 8GB VRAM would be more than enough for a single monitor @ 1920x1080 resolution.

In the next few months I’ll be running a single monitor at 3840*2160. Hence the need for max power from the graphics card.

11 minutes ago, Ray Proudfoot said:

Bob,

I appreciate you taking the time to write that but sadly deciding which RAM I should buy seems to require a degree in mathematics. Surely there must be a website somewhere where you choose the chipset of the mobo and select the processor and it shows you entry level, intermediate and top quality RAM.

The user then makes their choice with all the hard work done by the software. Does such a service exist? If not then with an Asus Prime Z370-A mobo and i7-8086K what are my best choices for middle to top end RAM. 16Gb now looking likely.

Aw, now, come on, 2000 times CAS level divided by speed in MHz--that's not advanced math.  <9 is high perf.  9-10 is better than average.  10+ average to below average.

ASUS publishes a QVL (qualified vendor's list) on their website that lists RAM they have tested with their boards.  Determining the performance of those listed modules is as simple as doing the math above.  You'll find that a little digging is necessary...on Newegg's website, for example, the RAM speed is listed in the product name, but you have to dive down to the more complete product description to see the CAS level.  It's part of that marketing ploy to get you to focus on speed and to keep the unknowing from asking about that danged newfangled CAS thingy.

 

I've been using 16GB for years and it has always been sufficient.  Having said that, I'll be getting 32GB when I complete my next upgrade in a few months. I'd rather have too much than not enough.

Dave

22 minutes ago, w6kd said:

Aw, now, come on, 2000 times CAS level divided by speed in MHz--that's not advanced math.  <9 is high perf.  9-10 is better than average.  10+ average to below average.

ASUS publishes a QVL (qualified vendor's list) on their website that lists RAM they have tested with their boards.  Determining the performance of those listed modules is as simple as doing the math above.  You'll find that a little digging is necessary...on Newegg's website, for example, the RAM speed is listed in the product name, but you have to dive down to the more complete product description to see the CAS level.  It's part of that marketing ploy to get you to focus on speed and to keep the unknowing from asking about that danged newfangled CAS thingy.

 

I just have a mental block when it comes to those timings, sorry. But lower CAS number is good so how about CAS 14 and speed of 3200Mhz. That should kick bottom! This looks like a good candidate

https://www.amazon.co.uk/G-SKILL-F4-3200C14D-16GTZ-Trident-DDR4-Memory/dp/B01ACODPHI/ref=sr_1_1?ie=UTF8&amp;qid=1540497601&amp;sr=8-1&amp;keywords=f4-3200c14d-16gtz

Edited October 25, 20187 yr by Ray Proudfoot

2 minutes ago, Ray Proudfoot said:

I just have a mental block when it comes to those timings, sorry. But lower CAS number is good so how about CAS 14 and speed of 3200Mhz. That should kick bottom! This looks like a good candidate

https://www.amazon.co.uk/G-SKILL-F4-3200C14D-16GTZ-Trident-DDR4-Memory/dp/B01ACODPHI/ref=sr_1_1?ie=UTF8&amp;qid=1540497601&amp;sr=8-1&amp;keywords=f4-3200c14d-16gtz

That's 8.75 ns RAM.  Reasonably high performance, but not cutting-edge.  A solid choice.

 

7 minutes ago, w6kd said:

That's 8.75 ns RAM.  Reasonably high performance, but not cutting-edge.  A solid choice.

But I thought CL14 made it fast. And given the cost you’d expect it to be. This is why choosing RAM is such a pain and that’s putting it mildly. 

If it’s a solid choice that will probably do me. 

23 minutes ago, Ray Proudfoot said:

This is why choosing RAM is such a pain and that’s putting it mildly.

It's not, you want the highest rated frequency at the lowest possible CL.  This usually means the modules will not fail under higher voltage.

Example 3200/14 = 228 … 4400/18 = 244 … (higher ratio is better) ...that's a little simplified but you get the idea … what you're paying the extra $$$ for is the memory not failing at higher voltage.  However, read the fine print as most memory manufacturers don't guarantee it will work at their state voltage and timings … we just have to sorta "trust them" or make sure there is a good return policy.

Cheers, Rob.

16 minutes ago, Rob Ainscough said:

It's not, you want the highest rated frequency at the lowest possible CL.  This usually means the modules will not fail under higher voltage.

Example 3200/14 = 228 … 4400/18 = 244 … (higher ratio is better) ...that's a little simplified but you get the idea … what you're paying the extra $$$ for is the memory not failing at higher voltage.  However, read the fine print as most memory manufacturers don't guarantee it will work at their state voltage and timings … we just have to sorta "trust them" or make sure there is a good return policy.

Cheers, Rob.

Thanks Rob. So in the two cases you gave 244 is the better memory even though it has a higher CL. It does seem that the higher the frequency the higher the CL. Having had a rethink it doesn't seem too complicated so I'll go to the G.Skill website and run some numbers.

As the rest have posted, Yes 16 ram is loads for Prepar3D. 

On a side note though,  My computer is now nearly 5 years old and has 16 of Ddr3 ram  (slow ram for today)    However I do use After effects and other Adobe stuff and these Apps are hard on memory ram, So when I treat myself to a new computer I will defo get 32 fast ram so i can potter around with my videos in extra comfort  

Currently I am only getting 8 (ish) seconds play back on full resolution using After effects

14 minutes ago, Ray Proudfoot said:

So in the two cases you gave 244 is the better memory even though it has a higher CL.

Correct, what they (memory manufacturers) do is adjust timings/voltage … so they increase how many cycles the memory "waits" before it can be refreshed with data, BUT they also increase the frequency of those cycles over a given period of time.  It's trading values to get the lowest possible latency.  In most cases, higher frequency means high voltage, higher voltage can trigger failures … it's a game they play … I have no idea if they test every single memory module at their rated speeds/timings nor what devices they use to do that (highly unlikely real motherboards) and I think that's why results vary when it comes time to actually install and use the RAM in any given MB.  

The QVL is a good place to start, but unfortunately those RAM identifiers in the QVL may not actually be the same as was what is available retail.  They are often provide to the MB manufacturer as "samples" and may not be what's actually released into the real world.

So if something is posted at 4400Mhz at 1.4v CL18 (via it's XMP) that doesn't always mean it will actually operate at that configuration in one's MB.  You hope it does, but it's not guaranteed.

Cheers, Rob.

@Poppet, thanks for confirmation v4 is happy with 16Gb. Nothing like hearing it from the horse's mouth. That doesn't mean I'm calling you a horse of course. But if you were you'd be a thoroughbred.

@Rob Ainscough, just when I thought it was a simple mathematical formula to find the best memory you thrown that spanner into the works!

Anyway, over the last hour I've gone many of the modules available at G.Skill for each speed and pasted the relevant data into an Excel spreadsheet. I used Tested Speed / CL to determine the ratio. I used the first number of 15-15-15-35 as the CL, hopefully correct.

The module with the lowest ratio was F4-2800C15D-16GTZ with a tested speed of 2800 and a CL of 15. Ratio = 187. Cost £187.

The highest ratio was F4-3600C15D-16GTZ with a tested speed of 3600 and a CL of 15. Ratio = 240. Cost = £338.

I'll check the prices of the other modules and I can probably devise a formula to come up with the best value for money. Thanks, you've been very helpful.

Here's my spreadsheet...

You're missing the 4400/18 (244) - this is what I have for my new build … I think there is a 4600 CL19 1.5v (242) and a Corsair 4700 CL19 (247) … 

These G.Skill F4-4266C17Q-32GTZR look interesting at 4266/17 (250).

The last one you listed looks like a pretty nice price to performance ratio: https://www.newegg.com/Product/Product.aspx?Item=N82E16820232306&amp;Tpk=N82E16820232306

Cheers, Rob.

Wow, what a great technical overload...you guys really know your stuff.

I was doing just fine with 16gig but recently added another 16 gig but not for P3DV4, but rather XP11 so I could handle flying HD ortho.

I7-6700K  4.2GHZ overclocked, GTX 970 4GB 7GHZ GDDR5, RAM 32G DDR4 2133MHZ, Win7 Professional, FSX, P3DV4+, XP-11
(G.SKILL Ripjaws V Series F4-2133C15D-16GVR DDR4 2133MHZ 32GB&#40;8GBX4)

But now this system is already looking really old...lol. Look at that video card!

As it turns out adding the extra 16gig, with my processes being managed by Process Lasso both sims are performing great and features turned up very high and extreme.

Bryan