i7-4790K having issues with DDR3-2400?

[Akrovah]

Hi! I am looking at my first full build in several years (I am still on Conroe) and am pretty much set on the i7-4790K. When picking memory I began to notice that the combination of Speed, CAS, and Size I could find the best value at DDR3-2400 Mhz CAS 10.

But now I am seeing in a couple of places people having issues running a 4790K at any memory speeds above 1866.

So does anyone here know, is there any truth to that? Do you have to OC the CPU to get to 2400 Mhz on the Memory? Has anyone gotten a 4790K with DDR3-2400 stable with or without overclocking?

Thanks for any advise and I apologize if this has already been covered! I tried a quick search but didn't find anything usefull.

 

[Yuriman]

We've tried 2133 with my brother's Haswell i5 and had no problems, but there isn't much point in buying RAM faster than 1866 because the gains are incredibly tiny. Haswell is not bandwidth bottlenecked in a vast majority of use-cases.

See here: http://www.anandtech.com/show/7364/memory-scaling-on-haswell/7

Spend the money elsewhere.

 

[Akrovah]

I know there's not a whole lot of point from a performance perspective (I've actually read the article you linked multiple times already), but right now G.Skill Dual Channel 16Gb Kit on Newegg:

DDR3-1866 - 179.99:
http://www.newegg.com/Product/Produc...-623-_-Product

DDR3-2400 - 174.99:
http://www.newegg.com/Product/Produc...-589-_-Product

And that seems to be a pretty common situation. At those prices I see no point in getting the 1866. But if I get the 2400, I'd like to actualy run it at that speed.

 

[BonzaiDuck]

I know there's not a whole lot of point from a performance perspective (I've actually read the article you linked multiple times already), but right now G.Skill Dual Channel 16Gb Kit on Newegg:

DDR3-1866 - 179.99:
http://www.newegg.com/Product/Produc...-623-_-Product

DDR3-2400 - 174.99:
http://www.newegg.com/Product/Produc...-589-_-Product

And that seems to be a pretty common situation. At those prices I see no point in getting the 1866. But if I get the 2400, I'd like to actualy run it at that speed.

It seems to me that a lot of these kits above 2133 run at 1.65V vDIMM. I think the inclination here -- among various old-timers -- is for RAM volted at 1.5 or lower. Since there's little gain to be had for speed over capacity, you could probably buy a set of G.SKILLs at 2400, tighten the latencies, drop the speed and volt them at 1.5V. You could buy the 2400-s and run them at 1866 at less volts. It seemed to me that an Intel "recommended" maximum RAM voltage for my SB-K is around 1.58V. It should be same for the Ivy-Bridge cores, and I can't see how it would be higher for the Haswell.

A lot of folks will probably say 1.65V is OK and fine.

You might as well take the time to look into these issues before you press the Checkout button.

 

[Akrovah]

See, and I kind of knew that somewhere in the back of my mind. Don't know how I forgot to look at voltage when looking at RAM.

Thanks for the advise!

 

[BonzaiDuck]

See, and I kind of knew that somewhere in the back of my mind. Don't know how I forgot to look at voltage when looking at RAM.

Thanks for the advise!

I think I came across a G.SKILL kit of DDR3-2133 running at 1.5V. Maybe the latencies were 9-9-9-something. I can't remember. I'd think, however, that the timings are looser than that . . .

. . . Must've been these:

http://www.newegg.com/Product/Produc...-757-_-Product

See that they're approved for your motherboard by using the configurator at G.SKILL.

 

[Yuriman]

I try to find 1.25v or 1.35v sticks for my builds, even if I sacrifice a bit of latency.

 

[ehume]

I try to find 1.25v or 1.35v sticks for my builds, even if I sacrifice a bit of latency.

There's actually a good reason for this. I got a pair of very low profile RAM sticks to make sure they stay out of the way of whatever air cooling I use.

Their XMP profile 1 is 1.35v. I have a Megahalems Rev C ATM and these sticks allow me to use a 140mm front fan. The same would be true for a tandem tower heatsink.

 

[IGemini]

There's actually a good reason for this. I got a pair of very low profile RAM sticks to make sure they stay out of the way of whatever air cooling I use.

Their XMP profile 1 is 1.35v. I have a Megahalems Rev C ATM and these sticks allow me to use a 140mm front fan. The same would be true for a tandem tower heatsink.

I have the same RAM though in the 16GB configuration. On a combo with my case I think I spent just $85 on the RAM (counting all the discount there). Having a closed-circuit cooler I don't need the clearance, it was the best-priced 16GB kit at the time.

People mistakenly believe they want their RAM rated for a higher voltage. Ideally you really want the best speed at the lowest voltage. JEDEC requires DDR3 to be able to handle 1.5V. I know this RAM can hit 1866@1.5v, some have hit 2133. Spending $170+ for 1.6V RAM is doing it wrong.

 

[rtsurfer]

Been running Gskill TridentX 2400 C10 1.65V on my 4770K since last November.
Everything is fine here.

I don't think a 4790K is going to be any different.

 

[BonzaiDuck]

Been running Gskill TridentX 2400 C10 1.65V on my 4770K since last November.
Everything is fine here.

I don't think a 4790K is going to be any different.

Oh. . . likely not -- going to be different.

Whatever the recommended voltage, latencies and speed -- it's probably a good idea these days to avoid departing from the specs unless you're reducing speed with tighter timings. Underlying that is the time it takes to thoroughly test new memory settings. that is -- the time it takes with 16GB or more . . .