Requesting Advice: What happens if I add a 2x4GB RAM with 2x8GB? Same speed, CL, Voltage, Bandwidth & Brand.

[PirateAndy]

So I've read a lot on trying to use RAM with different CAS Latencies/timings (e.g. 16-18-18 with 15-17-17 etc) but all other things being the same. The general consensus is it's 50/50 whether you get a stable set of sticks or not and by the sounds of it I'd rather err on the side of caution.

However I've not come across any threads that deal with the title of this thread, to my knowledge anyway:

What happens if I add 2x4GB RAM with 2x8GB? Same speed, CL, Voltage, Bandwidth & Brand.

Now the sticks I specifically have are HyperX FURY DDR4 16GB RAM Kit (2x8GB) 2666MHz CL15 DIMM (15-17-17) ... I was looking at a similar set but different amount of RAM: HyperX FURY DDR4 8GB RAM Kit (2x4GB) 2666MHz CL15 DIMM (15-17-17).

So would this be a better match in my system? Would this still be dodgy in some way I'm not aware of? Would I lose my Dual Channel XMP settings on the current sticks and they all reset to single channel?

Any advice would be of great help in this so thanks in advance for anyone willing to put their two-penneth-worth down.

 

[geofelt]

What do you have now?
What are you considering?


Ram is sold in kits for a reason.
A motherboard must manage all the ram using the same specs of voltage, cas and speed.
The internal workings are designed for the capacity of the kit.
Ram from the same vendor and part number can be made up of differing manufacturing components over time.
Some motherboards, particularly AMD, can be very sensitive to this.
This is more difficult when more sticks are involved.
That is why ram vendors will NOT support ram that is not bought in one kit.

If you do buy more disparate sticks, they must be the same speed, voltage and cas numbers.
Even then your chances of working are less than 100%

What is your plan "B" if the new stick/s do not work?

Sometimes increasing the ram voltage in the bios will make things work.

If you want 16gb, my suggestion is to buy a 2 x 8gb kit that matches your current specs.
Then, try adding in your old 8gb,
If it works, good; you now have extra ram.
If not, sell the old ram or keep it as a spare.

 

[PirateAndy]

What do you have now?
What are you considering?


Ram is sold in kits for a reason.
A motherboard must manage all the ram using the same specs of voltage, cas and speed.
The internal workings are designed for the capacity of the kit.
Ram from the same vendor and part number can be made up of differing manufacturing components over time.
Some motherboards, particularly AMD, can be very sensitive to this.
This is more difficult when more sticks are involved.
That is why ram vendors will NOT support ram that is not bought in one kit.

If you do buy more disparate sticks, they must be the same speed, voltage and cas numbers.
Even then your chances of working are less than 100%

What is your plan "B" if the new stick/s do not work?

Sometimes increasing the ram voltage in the bios will make things work.

If you want 16gb, my suggestion is to buy a 2 x 8gb kit that matches your current specs.
Then, try adding in your old 8gb,
If it works, good; you now have extra ram.
If not, sell the old ram or keep it as a spare.

I may not have been clear in my last post. I have HyperX FURY DDR4 16GB RAM Kit (2x8GB) 2666MHz CL15 DIMM (15-17-17) and I was wanting to splash out and upgrade to 32GB for reasons.

I was first looking at adding another 16GB of RAM via another HyperX FURY DDR4 16GB RAM Kit (2x8GB) 2666MHz CL16 DIMM (16-18-18) until I read up on RAM timings and the pit falls, since CAS Latency and timings are very important and you are chancing trashing something.

My next idea was a set of HyperX FURY DDR4 8GB RAM Kit (2x4GB) 2666MHz CL15 DIMM (15-17-17) due to the fact they are the same voltage, CL etc etc...

I was considering this as a next best thing as the 8GB kit is half the price of the 16GB kit (£65 as opposed to £130) and it's still a decent RAM increase from 16 to 24. But, before making a purchase came to ask the question in order that I don't make a potentially expensive mistake. I was not aware that with all other things being "the same", that even the fact they are even slightly different could still cause instability.

But that is why I came to ask because there's always someone with more knowledge/experience to draw from. I seems as though you have essentially answered my question in that it is just as dodgy to add a second 2 stick kit even if everything else is equal.

My backup plan is therefore save many, many more pennies for a full 4 stick kit in many, many moons time.

 

[geofelt]

You will be about as well off if you buy a second similar 2 x 8gb kit.
Adding 2 x 4gb has about the same odds of working.
The problem is that any second kit will not be matched and may not work together.

I can't guess the odds. I might suspect you are 80% likely to be ok.

What would you do if you proceed and find that nothing works.
If you buy from a place which will accept the return, you could take the chance.

I think you would be better off if you want to be certain, by buying the 2 x 16gb replacement kit and selling the old kit.
Or, you could even try and see if both kits play well together in which case you have 48gb.

 

[Calvin7]

Memory is guaranteed in the form sold. Other combinations you decide to make have no guarantee to be compatible together.

Combining multiple kits may cause the memory to be unable to operate at rated specifications. You are free to do your own compatibility testing with no guarantees.