DDR4: 2666mhz c15 vs 2800mhz c16

[Andrius227]

Hello. So yeah i am planning on building a new pc. I need to decide what ram to get. DDR4 is super expensive right now so i think i will go with a set of 16gb (4x4gb). It should be enough and if it's not, i will be able to add another 16gb later...

So i am looking at this:
http://www.corsair.com/en-gb/vengeance-lpx-16gb-4x4gb-ddr4-dram-2666mhz-c15-memory-kit-red-cmk16gx4m4a2666c15r
and this:
http://www.corsair.com/en-gb/vengeance-lpx-16gb-4x4gb-ddr4-dram-2800mhz-c16-memory-kit-red-cmk16gx4m4a2800c16r

I will buy one of them. The price difference is pretty big. But i'm not sure if it's worth it. One of them is c15, the other c16, does that even matter ? The speed difference is not big. So yeah, which one would be better ?

[_I_]

to compare ram kits

speed / cl = value (hgher = better)
2666 / 15 = 177
2800 / 16 = 175

not much difference between them

[Azza ☠]

With DDR3, for gaming purposes lower CL timing is better than overclocked MHz.

Just to give you some idea...

Optimal performance would of been:
1600MHz CL9 1.5V (Calculated performance: 178)

Peak performance would be:
1600MHz CL7 1.5V (Calculated performance: 229)
or
1866MHz CL9 1.5V (Calculated performance: 207)

Where as overclocked MHz would actually be slightly slower, the higher voltage is also damaging in some cases:
2666MHz CL13 1.65V (Calculated performance: 205)

As you see lower CL timing normally calculates to better overall performance. You can calculate it as already mentioned above ( MHz / CL = Value ), to get a better idea of what one is best. For gaming purposes I would suggest getting the lowest CL timing possible.

DDR4 is however lower voltage and double the bandwidth, I don't honestly know if that calculation would matter as much or even apply. If it does, I would personally multiple it by two, due to the major increase in bandwidth (For example: 177 performance would be 354 for DDR4, compared to DDR3).

To go even deeper... CAS Latency (CL Timing) is actually broken down:
15-17-17-35
vs
16-18-18-36

It's a good idea to check all those values (as some memory cheats, claiming to be low CL timing, but it's just the first value and the rest is high). Since the values are raised by just 1 each and voltage stays the same 1.2V, the 2800MHz could actually be the better performing. How much real-world difference, probably not much. The other 2666MHz appears to be much more popular, most likely because it's a better deal.

[Andrius227]

Interesting. I guess i will go for the 2666mhz, it's cheaper and i can still overclock it. And it will still be a lot faster than my current ddr3 1333mhz ram.

[Beelzemon]

DDR3 to DDR4 is a bit gimmicky now, i won't bother until Skylake comes out.

[rotNdude]

Andrius227 a écrit :

And it will still be a lot faster than my current ddr3 1333mhz ram.

Why do you say that? If the timings are twice as high, you're not seeing the big picture for performance. What are you buying for a CPU?

[Andrius227]

rotNdude a écrit :

Andrius227 a écrit :

And it will still be a lot faster than my current ddr3 1333mhz ram.

Why do you say that? If the timings are twice as high, you're not seeing the big picture for performance. What are you buying for a CPU?

It's gonna be an x99 system. And there are only 3 cpu's available for it so it would not be hard to guess.

It's gonna be Asus rampage v extreme with an i7-5930k.

And as far as i seen, c14 is the lowest as ddr4 go, and they cost up to 1500gbp for 64gb set too... So they are probably good.