Memory Single vs Double Rank DDR4

I'm shopping for an 8GB stick of DDR4 to go with the 4GB stick (I know) that I already have.
I haven't really grasped the concept of Rank, and how important it is when matching RAM.

My RAM is Crucial 4GB DDR4 2666 Ballistix Sport.

I can get 8GB sticks in Single or Double Rank, but have been confused by what I've read out there...

Somewhere said that Dual Rank was more compatible, but some boards will only take so many Dual Rank sticks before complaining thereby requiring Single Rank - I have 4 slots on a B250 mATX board.

 

In layman's terms the golden rules are -

• To avoid complications never mix and match dual rank with single rank memory.
• Always go for matched sets i.e. 4x4Gb, 2x8GB, 4x8Gb etc etc.
• Dual rank won't clock as high as single rank memory.
• Dual rank and Ryzen/Threadripper do not play nice.

 

Pretty much what Paul said.

Intel is more forgiving of mismatched RAM, but it's always at the back of your mind if you get a random crash.

Thaiphoon burner is a useful tool for identifying exactly what RAM you have

 

Use the motherboard compatibility list as your first port of call.

Dual rank can out perform single rank but will typically do so at lower clock speeds, the most compatible ram for ryzen tends to be Samsung based single rank stuff but there is a benefit to Dual rank for same clock speed and timings.

But again check motherboard compatibility, it will save you pain, it took me 2 weeks of arsing about to get my RAM stable and fast because I did not do this.

Ryzen has had a few AGESA updates since so it may be easier now but why risk it.

I mixed single and dual on my 3770k, again that was a pain to get stable as I did not know about such things back then and assumed instability was because of 4 DIMM load, assumed I could throw any DDR3 2400 in and it'd be fine.....Doh!

I'll say a third time check motherboard compatibility lists

Some old stuff here, should still be relevant but not sure what later updates brought to table, my system is fast, stable and works, I'm not updating the BIOS......ever

https://community.amd.com/community...emory-oc-showdown-frequency-vs-memory-timings

 

Thanks guys, a lot of really handy stuff there.
It sounds like Rank is a bit like the old single and double sided RAM that I recall...

I'd heard about Ryzen being picky about RAM, and Samsung B Die being the thing to choose.

Dual rank can be faster at slow speeds, but Single rank can clock higher on OC, don't mix Single and Dual sticks - got it.

So Sandys, you think I may benefit from consulting the compatibility list?? I wasn't 100% sure from what you posted!!!!!
Srsly, that link to frequency vs timing was very useful, as I have asked myself that question on numerous occasions.

OK, my requirements are a mess by the look of it.
I bought a cheap (early £20 something posted) used 4GB stick of DDR4 (as mentioned) and was going to bump the RAM up on this board before replacing the CPU.

The rub is that I was considering a 'matched' (speed and model) 8GB stick, as it's entirely possible that my plans this year will include a move from mATX to mITX.
The s1151 mATX rig has 4 slots, so I could get a 2nd 4GB stick for dual channel, and then something bigger to get the size up.
But, if I'm moving down to 2 slots, I should be buying higher capacity sticks to maximise the future ITX capacity.
With the price of DDR4, I wasn't wanting to buy twice....

 

Ah yours is an Intel board I didn't twig...doh, I thought B250 was AMD but that is B350, sorry, Intel is much less picky but yes go for 2 bigger sticks as loading the memory controller can still limit performance when fully populated and will be totally reliant on your memory controller.

Intel platform is less reliant on memory performance vs the AMD platform.

 

No problem, thanks again for the info.
Chipset naming - it's not good what they've done, if you're forgetful like me, it's tricky to know what is from whom.

I'd love to have a crack at Ryzen, but even my 'elderly' i5 4670K seems to give Ryzen quads and hexes a good run for their money in games an a lot of things that aren't fully multi threaded.

The price of fast and compatible DDR4 is still seriously expensive, so Ryzen is off the menu for a good time yet.

Regretting winning that 4GB stick on ebay now, it was cheap, but is going to cause me grief in the long run (not to mention buying a cheap motherboard and S1151 Pentium to run it with...)

I need a super cheap matching 4GB to go with it, then go 8GB later - decisions decisions!

 

OK, back on DDR4 for intel 6/7th Gen.
Another old Chestnut if I may - should I buy a 16GB stick for now and have room on an ITX board for a second one or 2x 8GB and have the benefit of Dual channel?
I don't need more than 8GB for gaming, but one of my requirements is for photo editing of sub 20 MPix camera files

 

Thanks Mr H, will I 'really' lose much by putting a single 16GB stick in for starters? My understanding is that dual channel is a 10+% boost, not double...

 

That's a good assessment, thanks Gareth. I may even be able to afford fast DDR4 when I get to buying a pair of 16GB sticks in that case! I do feel relieved that I'm not shopping for Ryzen RAM, as that is a heart in mouth operation if you want fast sticks to get the best out of the system.
My current board supports 2133 with Skylake and 2400 with Kaby CPUs. I may go for something faster in case I jump to 'Z' series board (thinking about a used i5 6600K for the same reason) - it looks like HyperX 2933 RGB is only marginally more expensive than what I was looking at...