DDR3 vs DDR4 real difference? (with Asus Z170 PRO Gaming)

[Lideln]

Hi there,

I am willing to upgrade my computer from an AMD FX-8320 to an Intel Core I7 6700K (I have a GTX 970 graphics card).

From what I've read on the Internet, the Asus Z170 PRO Gaming seems a valid choice for MB.

However, I'm still wondering about RAM. Should I keep my 16GB DDR3 10-12-12, or should I switch to DDR4?

Something that got me confused, is that DDR4 is said to be much faster blahblahblah, and I wouldn't mind buying some, but when I have a look at benchmarks, DDR4 seems slower than DDR3.

How could it be?

Well, anyway, if you have (not too expensive, because 530€ for MB + CPU is already a big sum for me) advices for RAM (based on the assumption that I need to remove my current RAM), I'd be very happy to hear them! Also, is 2x8GB enough? (I am a heavy user, but currently my 2x8GB is more than enough for me)

For example, would these be ok?
* G.Skill RipJaws 5 Series Rouge 16 Go (2x8Go) DDR4 3200 MHz CL16
* Corsair Vengeance LPX Series Low Profile 16 Go (2x8Go) DDR4 3200 MHz CL16 - CMK16GX4M2B3200C16
They are not expensive, which is great for me

Thanks a lot!

 

[MatthewGB]

No, it's not worth buying one over the other. The RAM has almost no effect whatsoever on actual performance, so just get whichever DDR version is compatible with your motherboard, and then the cheapest speed (DDR4 is 2133MHz and DDR3 is 1066 or 1333 I think)

 

[Nick_50]

That motherboard only supports DDR4 so you will have to buy new RAM if you upgrade. The two you have suggested seem fine, on an ATX motherboard you have 4 slots for RAM so you can always add more RAM in the future if you need to.

You may not need faster RAM above the 3000Mhz speed, depending on what you do with your PC you might be able to stick to the standard 2133Mhz speed.

 

[Kurz]

DDR4 is pretty cheap now go ahead and switch. Try to sell the DDR3 ram, as thats good for life.

 

[MatthewGB]

Buy the cheapest DDR4 RAM you can find. The RAM you suggested is more expensive then need be.

 

[InvalidError]

You cannot use your 1.5V DDR3 RAM with Skylake. Although it may work, Skylake's memory controller is only rated for 1.35V DDRLL and using 1.5V DDR3 with it may fry its memory controller.

So you'll either have to attempt running your existing memory at 1.35V and replace it with DDR3L if that fails or give up on your current DDR3 and get DDR4.

There is very little benefit in pushing DDR4 beyond 2400MT/s, just as there was very little benefit in pushing DDR3 beyond 2133MT/s with older CPUs, so I wouldn't lose much sleep over which DDR4 memory to pick beyond 2400MT/s, I'd only go faster if it was only marginally more expensive without compromising on effective latency. Also, keep in mind that Skylake's memory controller is only officially spec'd for 2133MT/s anyway, you'll have to overclock the memory controller to go higher than that.

 

[blazorthon]

I wouldn't get DDR3-1066. It can be a bit of a bottleneck. DDR3-1600 is the "sweet spot" for DDR3 while DDR4 doesn't really matter because it starts much faster than DDR3.

Don't worry about synthetic performance, there's probably something wrong with that benchmark. Sandra would be a better example for a benchmark for memory. DDR4 has higher frequencies, ergo it is generally faster. Timings are higher, especially for the cheap DDR4, but keep in mind that timing is measured in clock cycles, so they aren't constant. For example, DDR3-1066 9-9-9-24 has the same latency measured in real time as DDR4-2133 18-18-18-48. DDR3-1600 9-9-9-24 has lower latency than DDR4 2133 15-15-15-35, as one example, but only slightly and it has much lower bandwidth than the DDR4 module, which is generally more important.

However, memory is generally not a big deal. Modern CPUs are not very sensitive to memory performance.

Regarding whether you should keep your current RAM or replace it, Skylake only supports DDR3L- low voltage (1.35V) DDR3, not the normal DDR3 (1.5V) you see in most places. If your RAM is a higher voltage than 1.35V (probably yes), then you would be out of recommended spec and that may shorted the CPU's usable lifetime. How much is anyone's guess.

 

[jayambroziak]

Actually, if you get DDR4 3000Mhz or faster memory, it IS actually faster and better than DDR3 1600Mhz. Not by much, but, 5% or more, depending on the speed. Your choice.

 

[InvalidError]

Actually, if you get DDR4 3000Mhz or faster memory, it IS actually faster and better than DDR3 1600Mhz.

DDR4 2133(-11-11-11) would already be faster in every way than DDR3 1600(-9-9-9): 34GB/s vs 26GB/s memory bandwidth (+33%) and 10ns vs 11ns (-9%) latency.

 

[MatthewGB]

But it will barely affect real performance. Around 2-3% in games.

 

[Isokolon]

it's not like it's making much of a difference.
synthetic benchmarks don't usually show the full picture, in application benchmarks DDR4 usually beats DD3.
but using skylake with DDR3L gives you any kinds of troubles and is not recommended anyway

 

[jayambroziak]

Actually, if you get DDR4 3000Mhz or faster memory, it IS actually faster and better than DDR3 1600Mhz.

DDR4 2133(-11-11-11) would already be faster in every way than DDR3 1600(-9-9-9): 34GB/s vs 26GB/s memory bandwidth (+33%) and 10ns vs 11ns (-9%) latency.

Actually, latency comes in to play and can hinder performance in DDR4 because of how long the CPU has to wait, per cycle.

 

[blazorthon]

Actually, no. Those cycles are measured in the memory's frequency and DDR4's higher frequency (in that example) more than negates it such that DDR4-2133 11-11-11 would have lower latency as measured in CPU cycles.

However, I don't think DDR4-2133 even comes with 11-11-11 timings. More common is 15-15-15-35 or 14-14-14-w/e which would be higher latency than DDR3-1600 9-9-9-24. However, there are a lot of much lower latency DDR4 modules that have higher frequencies. For example, DDR4-2800 15-15-15-35 is readily available and that's slightly better than DDR3-1600 9-9-9-24 in terms of real time latency.

 

[InvalidError]

Aside from latency, there is also the matter of CPUs accessing the RAM in 64-128 bytes cache line blocks, with means 4-8 DRAM cycle bursts. This makes the per-word cycle time 4-8X more important for burst read/write completion time as the initial access setup latency. Higher latency 2400MT/s DDR4 may take 1-2ns longer to access than 1600MT/s DDR3 but it will complete the actual 4-8 words data transfer bursts 2-4ns quicker, so you still come out 1-3ns ahead on total read/write completion time.

 

[Lideln]

Wow, this forum IS active! And you confused me with all your technical discussion

What I pick up from your answers is that I should definitely take DDR4 and that 3400MHz or 2133MHz will be (almost) exactly the same for me, and I should therefore take the cheapest one. It makes me (genuinely) wonder why there are so many expensive RAM sticks, but I totally trust all of you guys, and I'll pick any cheap DDR4 2x8GB RAM

Thank you all for your answers! (difficult to "pick as the solution" a single answer as you seem to all agree, for the most part anyway)

 

[InvalidError]

It makes me (genuinely) wonder why there are so many expensive RAM sticks, but I totally trust all of you guys, and I'll pick any cheap DDR4 2x8GB RAM

What balance of clock frequency and timings yields the best performance varies on a per-application/game basis. Unless you have very specific requirements, you won't notice the difference in most everyday uses. Even in DRAM benchmarks, the gaming performance difference is only noticeable when you look at corner-case stats such as "1% frame time variance" which are most sensitive to bandwidth-vs-latency balance. Even there, the choice still isn't one-size-fits-all.

Getting something better than the cheapest memory available won't hurt, but it isn't worth paying a significant premium for it unless you have a specific reason to. If it costs you only a few extra bucks to step up from 2133 to 2400 or 2666 with similar latency, having more options at negligible extra cost won't hurt.