Please help me with overclocking and RAM/MBoard compatibility

[Bogdanov89]

[FONT=&quot]I am having trouble understanding all this stuff about overclocking RAM and motherboards that support it.[/FONT]
[FONT=&quot]For my new gaming PC i can buy either:[/FONT]

• [FONT=&quot]DIMM DDR3 2x8GB 2400MHz Kingston HyperX Savage CL11[/FONT]
• [FONT=&quot]DIMM DDR3 2x8GB 1866MHz Kingston HyperX Savage CL9[/FONT]

[FONT=&quot]For my new motherboard i can choose between:[/FONT]

• [FONT=&quot]LGA1150 Z97 ASUS SABERTOOTH Z97 MARK 2[/FONT]
• [FONT=&quot]LGA1150 Z97 ASUS Z97-PRO GAMER[/FONT]
• [FONT=&quot]LGA1150 Z97 MAXIMUS VII RANGER[/FONT]
• [FONT=&quot]LGA1150 Z97 ASUS Z97-AR[/FONT]

[FONT=&quot]My CPU will be Intel i7-4790K and my PSU is a 750w Seasonic SS-750AM2, GPU is Nvidia GTX 980.[/FONT]
[FONT=&quot]I understand that CL9 is better than CL11, but the entire overclocking thing baffles me.[/FONT]
[FONT=&quot] [/FONT]
[FONT=&quot]What really confuses me is the following:[/FONT]

1. [FONT=&quot]Sabertooth motherboard does not seem to support 2400MHz RAM - but it does support 1866MHz RAM without overclocking, or am i mistaken?[/FONT]
2. [FONT=&quot]The other 3 mother boards support up to 3000+MHz RAM, but they do not support 1866MHz RAM without overclocking?[/FONT]
3. [FONT=&quot]I do not understand how RAM overclocking works, do i sacrifice my CPU performance (or something else) when i overclock my RAM to 2400MHz?[/FONT]
4. [FONT=&quot]If the 2400MHz RAM is left to work at only 1866 MHz, does it still have CL11 - or does the latency drop to CL9 since it runs on 1866MHz?[/FONT]
5. [FONT=&quot]Which motherboard would be the best choice if i want to run a 1866MHz RAM at CL9?[/FONT]
6. [FONT=&quot]Which motherboard would be the best choice if i want to run a 2400MHZ RAM at CL11?[/FONT]

[FONT=&quot]I am not able to understand which RAM should i pair up with motherboard for maximum performance?[/FONT]
[FONT=&quot]The prices are very similar, so money is not the problem here - i just don't understand which RAM+Motherboard would give the best performance in games like Battlefield 4 (64 multiplayer).[/FONT]
[FONT=&quot] [/FONT]
[FONT=&quot](side question): what is better for a single Nvidia GTX 980 GPU, a PCI (32-bit) slot or a PCI-Express 16x slot?[/FONT][FONT=&quot][/FONT]

 

[Ken g6]

it does support 1866MHz RAM without overclocking, or am i mistaken?

Standard RAM speed for Haswell is 1600MHz. Anything higher is overclocking. Period.

do i sacrifice my CPU performance (or something else) when i overclock my RAM to 2400MHz?

Overclocking RAM tends to limit overclocking of the CPU on Haswell.

For gaming, memory speed usually doesn't matter that much at high resolution with a discrete GPU:

http://www.anandtech.com/show/7364/memory-scaling-on-haswell/7
http://www.xbitlabs.com/articles/memory/display/haswell-ddr3_7.html

If there is a tradeoff between memory speed and CPU speed (and there can be), CPU speed is probably better. Are you sure you still want to OC your RAM? Though it doesn't hurt to get RAM capable of faster speeds at 1.5V if it's not significantly more expensive than other RAM.

(side question): what is better for a single Nvidia GTX 980 GPU, a PCI (32-bit) slot or a PCI-Express 16x slot?

Modern high-performance GPUs only fit in one kind of slot: PCI-Express 16x.

Edit:

If the 2400MHz RAM is left to work at only 1866 MHz, does it still have CL11 - or does the latency drop to CL9 since it runs on 1866MHz?

Actually, this is an interesting question. CAS latencies are measured in cycles. RAM speeds are cycles per second. MHz is a million cycles per second, or one cycle per usec. So the question is whether:

11 cycles/(2400 cycles/usec) < 9 cycles/(1866 cycles/usec)?
0.0046 usec < 0.0048 usec?

Yes, the RAM will work like that.

 

[tenpole]

Standard RAM speed for Haswell is 1600MHz.

I thought my Pentium G3258 had slower ram speed or does the Pentium not count as a haswell chip. Or have I got it all wrong.

 

[DrMrLordX]

The G3258 and other Pentiums do have a lower default memory speed (DDR3-1333). They are Haswells, just from a lower-tier product category.

That being said, you can stick a G3258 on a Z97 board and get full memory overclocking, if you really want it.

 

[flexy]

Those RAM sticks are more or less the same, in terms of performance there won't be a noticeable difference between the 2400MHZ sticks at CL11 and the 1866 sticks at CL9.

I would however say the 1866 sticks look better since I am sure that *IF* you want to overclock them, the 1866 sticks might make 2000 at CL10. (It is really a trade-off between speed and latency CL). But as said, in reality this difference will be microscopic and would only show in benchmarks. (Of course it also possible that the 2400 sticks could be "downclocked" to 2000 and run at CL10 also) But ultimately it's really the same...

Modern sticks should have "XMP Profiles" with optimal timings in them which you should be able to activate within your BIOS, so you don't really need to worry too much there.

* I can't say anything about boards EXCEPT that the Asus Z87 Pro is VERY solid and overclocks well so I would give preference to Asus.

* Overclocking your ram (or your CPU) does indeed sacrifice "a bit" of each other but it's also not too significant in my opinion. I personally have not seen that running my memory slower would increase my CPU's (4770k) performance. It stays a rather mediocre overlocker no matter what. (Maximal 4.5GHz, and running ram slow doesn't change that )

* PCI Slot: Hardy ANY component today uses the outdated PCI Slot. Most boards don't even have it any more. ALL halfway modern graphics card from the last 10 years and sure your GTX use a PCIE x16 (PCIE == PCI Express) slot. (PCI slot only makes sense should you have a very old sound card or whatever other very old PCI card laying around where you would want the slot because you don't want to buy a new soundcard with a PCIE connector)

* The BIOS will also give you options to set timings for your RAM, say you COULD run your 2400 lower at 1866 but then you could also manually set it to CL9. (Of course this is not necessary, but you sure could do this. In such an odd scenario you would of course not want to run memory at 1866 with CL11, 11 latency only at high speeds, why run ram "slow" and keep the high latency?) As said above, get the 1866 and run it at C9 and be happy!