RAM configuration question

[XDXD_4U3IF1P]

Hi All,

 

A chance for me to learn re my new config -

 

Let's say a game uses 6GB RAM max at times.

 

And we are working with a total of 16GB RAM (assume speed and latency is the same for all configs).

 

Three scenarios of RAM config.

 

1. 1 x 8GB stick

 

2. 2 x 8GB sticks

 

3. 4 x 4GB sticks

 

Would the 3rd option perform best, even tough the game draws more than a single stick of the total RAM?

I guess the gains will be small, and assume it depends on the game code but generally speaking is there a return in higher FPS?

[Sakkura]

Depends whether the platform supports quad channel. But realistically the gains between dual channel and quad channel will be absolutely minimal. So 2 and 3 will perform best, with 1 usually pretty close.

[XDXD_4U3IF1P]

so diminishing returns, but not a problem with config 3?

 

[typographie]

8 minutes ago, ShoshinUK said:

Would the 3rd option perform best, even tough the game draws more than a single stick of the total RAM?

I guess the gains will be small, and assume it depends on the game code but generally speaking is there a return in higher FPS?

Option 1 would be single-channel mode. Option 2 would allow dual-channel mode on mainstream systems. Option 3 would allow for dual-channel mode on mainstream systems or quad-channel on X99 systems. As far as gaming performance the difference is marginal at best, though you should aim for dual-channel at least just because it costs you basically nothing. There is no benefit to option 3 on a mainstream system that I know of, and it would make future upgrades less convenient due to having all slots filled.

 

Even in a very unusual situation where a game is actually memory-starved, it's not usually your second-by-second framerate that takes the hit. You'll notice it in increased stuttering when approaching new areas, or when changing camera angles quickly.

[ChrisCross]

3 minutes ago, ShoshinUK said:

...

the third option has the highest bandwidth. but since ram bandwidth is no bottleneck when it comes to any normal usage it will make absolutely no difference at all. go for the cheapest option 1x8gb , maybe 2x8gb is your a tab monster

[paddy-stone]

No problem with config 3, but IMO it#ll be a waste of resources down the line... what I mean is with scenario 2 you can still expand your RAM total capacity with another 8GB stick or 2, with scenario 3 you'd have to get all new RAM sticks to increase capacity, so I'd always go with 2. Unless of course you upgrade your PC every year or 2, in which case the point is probably moot.

[Sakkura]

4 minutes ago, ShoshinUK said:

so diminishing returns, but not a problem with config 3?

 

No problem at all. The data gets spread across the sticks by the way, it's not like one gets filled and then things somehow slow down once the next one is being filled etc.

 

In fact spreading the data across the sticks improves performance, because with dual or quad channel it can interleave access - so instead of having to eg. read 6GB consecutively from one stick, it can read 3GB in half the time from each of two sticks, or 1.5GB in a quarter the time from each of four sticks.

 

Games are not memory-dependent enough to really benefit from quad channel at all though, and dual channel is only a modest advantage. But no need at all to limit yourself to single channel with a single stick of memory.

[typographie]

5 minutes ago, paddy-stone said:

... with scenario 3 you'd have to get all new RAM sticks to increase capacity, so I'd always go with 2.

You'd only have to get two new sticks, technically. Only each pair has to match in a dual-channel configuration, not all four.

[paddy-stone]

 

1 hour ago, typographie said:

You'd only have to get two need sticks, technically. Only each pair has to match in a dual-channel configuration, not all four.

 

I know they don't have to match, but either way he would still be having to ditch 2x 4GB sticks to put in 2x8GB in that scenario.. much better IMO to put 2x8GB and just expand as needed.

[XDXD_4U3IF1P]

It's for a new build where my budget is open, i'm happy to invest to get the absolute best FPS and related performance across games like Arma and Squad, both CPU intensive and top out at about 6GB RAM used.

 

To give you an idea where my FPS addiction is, if it cost me say £250 extra, to gain 5FPS and have less stuttering I would happily pay it as I play games at a fixed FPS to avoid the highs and lows, and I want that fixed FPS to be as high as possible.

 

So we are saying that 4 x 8GB may perform a little better than 2 x 8GB due to the increased bandwidth for the Application to draw from, even when the game only needs 6GB at times? 

[porina]

We're getting into very niche territory here. The basics on dual vs. quad channel ram have been covered, but I don't see mention of memory rank.

 

In the case of a dual channel memory system, option 3 would give you 2 rank per channel, and option 2 depends on the specific modules, as some are single rank, some are dual rank. What does rank do? In tests dual rank increases bandwidth but also increases latency. So if you want to go that way depends on how the application behaves. 4 modules in dual channel mobos seem to have more potential for instability if running at very high speeds. I believe single rank is also more overclockable, if you're going into that.

 

Quad channel system really deserves option 3.

[XDXD_4U3IF1P]

ok thanks all for the help on this, please feel free to add any supporting info on this somewhat specialised subject as I am learning alot!