i7 4790k and memory - ddr3 1333 vs. ddr3 2800 (please explain all the numbers) :)

NYCSwede · Mar 6, 2015

Hi all,
Starting a new build - (uses - browsing, Office, a lot of photoshop, some gaming - Dying Light, Titanfall)
i7 4790k
Gigabyte GA-Z97MX-GAMING LGA1150 mATX mobo (memory range from ddr31333 to ddr33100)

For now I'll use the memory I have from my old system (total 16gb)
ddr3-1333
1 set 2x4gb - (PNY Optima 8GB (2 x 4GB) 240-Pin M DDR3 1333 (PC3 10666) http://

1 set 2x4gb - (G.SKILL Ripjaws Series 8GB (2 x 4GB) 240-Pin DDR3 SDRAM DDR3 1333 (PC3 10666)) http://www.newegg.com/Product/Product.aspx?Item=N82E16820231311

I do not plan on overclocking the CPU at this time, or I might just OC a very small amount just to get it over 4Ghz. Its a microATX case so I'm trying to keep the cooling simple - I picked up a Zalman CNPS8000B Low Profile CPU Cooler.

My questions are -
I've read in older posts while searching for answers to this question that unclocked CPUs only utilize faster memory (ddr3-1800 and above) if the CPU is overclocked itself.
Is this true with a 4790k? (what is it's default speed?)
So for example - If I leave it at stock speed, I would not see a difference from different memory - either the DDR3-1333 or if I put in DDR3-1600 or even DDR3-2800?

Do I have to (or can I) change the speed of RAM in Bios? I read somewhere that even 1600 memory will run at stock 1333 unless changed in BIOS.

The specs for the memory I have show the following
Cas Latency - 9
Timing 9-9-9-24-2N
Voltage 1.5V
Multi-channel Kit - Dual Channel Kit

What do these specifically mean?

And how do they compare with this DDR3-2800 memory listed on newegg -
http://

Cas Latency - 12
Timing - 12-14-14-36
Voltage - 1.65V

I'm trying to understand the benefit of $325 memory over $120 memory (my set of 4 4 gig chips)

Thanks for any and all info!!!!!!

Peter

AdviserKulikov · Mar 6, 2015

Faster RAM has few benefits, for graphics processors without dedicated VRAM it uses the system RAM and faster RAM will see a significant benefit. For systems with a dedicated GPU, it may see slight benefit, but it quickly disappears as graphical load goes up and the limiting factor is GPU performance.

Otherwise, just make sure you have enough. There is never any reason to exceed what your cpu or motherboard supports either. Some non gaming programs will see benefit.

NYCSwede · Mar 6, 2015

Thanks!
I should mention I also have a gtx780 3gb video card.

Can I mix memory? can I have 8gb of DDR3-1333 in one bank and put in 16gb of DDR3-1600 in the other bank?
Would I really see any improvement if I increase memory from 16gb total to 24gb or 32gb?

AdviserKulikov · Mar 6, 2015

NYCSwede :

Technically you can mix memory kits (this used to be a big no no that would cause problems, it's now doable), however you will lose more performance the bigger the difference between them as it needs to find the lowest common performance between them. I would advise at least finding kits with the same GB/stick and clock rate. Optimally you buy one kit, second best is to buy kits with identical capacity, clock rate, timings and voltage.

There's nothing stopping you from trying putting both of those kits in together, the motherboard should manage it automatically. Mixing kits may have one or two sticks not work with the others.

JackNaylorPE · Mar 6, 2015

1. Intel has a thing called XMP which stands for "Xtreme Memory Profile". If you buy a set of RAM advertised as DDR3-1600 then 1600 is the XMP or "overclocked profile". So now you do not have to run the CPU overclocked to enjoy XMP, 99% of PC builds out there are running XMP (officially overclocked) RAM.

2. There seems to be nothing that anyone can do to stamp out the myth that faster RAM does nothing. This statement has been parrotted down thru the years from the early days of DDR-3 for example when 1600 RAM was $90 and 2400 RAM was $180. Many reviewers stated that the increase in RAM performance (averaging say 2-4%) was not worth the 100% or more price increase. This is false reasoning in today's world for 2 reasons:

a) The price structure has changed. Today you can oft buy DDR3-2400 for within $2 - $5 of DDR3-1600.

b) Faster RAM just doesn't make the RAM faster, it's the whole system that goes faster. So in yesteryear, going from 1600 - 2400 RAM on a $2k box was not a 100% increase in cost, it was a 5% increase in cost.

So, yes, today buying 2133 or 2400 RAM is the proverbial "no brainer". Dumping what ya got for something faster .... that's a harder question that in reality depends on your disposable income more than any advice you can get here.

3. The "no significant effect" statements also come from gaming test which is this site's biggest audience. On CAD, video editing, rendering, encoding, Adobe products, large database and spreadsheet manipulation, faster RAM does have a very significant effect. In gaming it's bit trickier.... most reviewers look at average frame rates on single cards where the performance bottleneck lies elsewhere.... test again with SLI ... test again with minimum frame rates and things change.

4. In gaming, again at average fps, results vary widely. In games like Metro LL where the GFX card is the bottleneck, faster memory has 0 impact. But look at a game like F1 and we see a whopping 11% increase in frame rated going from 1600 to 2400 RAM. Again when the cost difference is so small, it's an easy choice.... tho as peeps have realized this in recent months DD3-1600 prices have started to tumble

http://www.tomshardware.com/reviews/32-gb-ddr3-ram,3790-10.html

Cheapest set of DDR3-1600 CAS 9 Ripjaws on newegg is now $130
Cheapest set of DDR3-2133 CAS 9 Ripjaws on newegg is now $150
Cheapest set of DDR3-2400 CAS 10 Tridents on newegg is now $150
Cheapest set of DDR3-2666 CAS 11 Tridents on newegg is now $190
Cheapest set of DDR3-2800 CAS 12 Tridents on newegg is now $400

So while the cost jump from 1600 all the way to 2400 is quite small...to 2666 reasonable, the jump to 2800 is hard to justify unless you are benefitting from using the machine in a production environment where there's an ROI. That tipping point has changed over the years as production line yields improve over time. When DDr3 first came out, 1600's yield wasn't great and yields above that shrank with the speed increase. Now 2400 has got to be about where 1600 was back then.

2 x 8GB is superior to 4 x 4 GB on dual channel boards as it puts less strain on the IMC (memory controller).

To see the effect of latency... CAS x 1000 / DDR speed

2400 CAS 10 = 10 x 1000 / 2400 = 4.17 nanoseconds
2133 CAS 9 = 9 x 1000 / 2133 = 4.22 nanoseconds

I would not buy a 4790k if I was going to leave it at stock speed....especially with the apps you're running.

ll you have to do in the BIOS to enable XMP (memory overclocking) is to enable XMP in the BIOS. really not much to it.

Again, yes, all 1600 memory will run at 1333 unless XMP is enabled in BIOS. You **can** mix 2 x 1333 and 2 x 1600 sets but will have to down clock the 1600 set to run at the 133 set's speed and timings in the BIOS.

Before I'd jump from $150 overclocked RAM to $400 overclocked RAM, I'd certainly be overclocking the CPU to at least 4.5 GHz .... the faster CPU will have far more wide ranging effects than the 2800 RAM ... the savings even pays for $150 water cooling system (H240-X) and puts $100 back in your pocket .... or a Phanteks $60 air cooler and $190 back in your pocket

BTW, the reason that the RAM is considered overclocked, is because the technology has outstripped the standards. JEDEC the industry standard has to this point not yet gotten passed approving anything beyond 1866 profile.

If someone says you can't go beyond 1.5v, stop reading .... the 1.5v applies only to JEDEC profiles, not XMP. When DDR3 came out, every single set of DDR3-1600 was 1.65 volts. If you want "official proof" go here:

http://www.intel.com/content/www/us/en/gaming/extreme-memory-profile-xmp.html

Click on the PDF or excel link on the right side of the page and you will find that well over half of the "officially certified compatible RAM sets" listed on the "Certified Intel i5/i7 Compatibility List" are over 1.5 volts.

More RAM is always better.... but going to 4 sticks may reduce your CPU OC due to the extra load on the IMC. It will come in handy on large files PhotoShop if doing in several hours a day might be worth it.

martinch · Mar 6, 2015

NYCSwede :

I kinda read the opposite - the more you OC the CPU, the slower (less overclocked) memory you can use.

NYCSwede :

Haswell "formally" supports up to 1600MHz DDR3, with anything else being considered "overclocked", although its commonly stated most Haswell i7's will handle 2133MHz just fine.

NYCSwede :

Anandtech did an article on this, which is probably worth a read - http://www.anandtech.com/show/7364/memory-scaling-on-haswell. From what I remember, image editing benefits from high-bandwidth memory.

NYCSwede :

You'll want to enable XMP.

NYCSwede :

CAS latency is the number of cycles before the memory does something (read, write, etc) - essentially the delay between a command being issued, and it starting to do it, so the lower the better, although a higher latency can be compensated for by increasing the clock rate (using the higher bandwidth to compensate for the latency). Having said that, it's often said it doesn't make much/any noticeable difference. The timings are essentially a more detailed expression of the latency.

https://en.wikipedia.org/wiki/CAS_latency
http://en.wikipedia.org/wiki/Memory_timings

The voltage is the voltage required by the chips - this should not be more than 1.5v, as that's what the memory controller's rated to. It being dual channel means that when installed in pairs, data will be striped across them, yielding better performance.

NYCSwede :

Generally, faster memory is better, but it's generally not worth spending much extra on. I'm not sure what the prices are up to at tha moment, but when I bought mine, 1600MHz C9, 1866MHz C9, and 2133MHz C11 (Corsair Vengeance Pro) were all the same price, so I went with the 1866MHz. For the price difference you've illustrated, you could probably move to X99, which might be a better way of spending the extra money (massive memory bandwidth & I'm guessing Photoshop is sensibly multi-threaded so will take advantage of the 2 extra cores).

P.S. That 4790 should tear through Photoshop (mine flies through Lightroom).

AdviserKulikov · Mar 6, 2015

As Jack said, there is definite performance improvements in non gaming applications, however I feel like the system is fast enough as is to not justify upgrading the RAM speeds when you having older stuff laying around.

I am of the opinion that if you have 1333 or faster DDR3, and do not do stuff like aftereffects for a living then you can make it until you need DDR4 for a new motherboard.

If you have an extra $200 burning a hole in your pocket, and your PC is otherwise kitted out, it's not bad to upgrade RAM to better stuff.

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i7 4790k and memory - ddr3 1333 vs. ddr3 2800 (please explain all the numbers) :)

NYCSwede

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JackNaylorPE

AdviserKulikov

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NYCSwede

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AdviserKulikov

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JackNaylorPE

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martinch

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AdviserKulikov

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