Can I use DDR3 modules with different timings and Cas latency?

Zorba Greekthe · Dec 15, 2014

I already have a pair of Adata AX3U1600C4G11-SD 4GB modules from TigerDirect. For some reason I cannot find the full specs on them, not even from the Adata website.
I am guessing that the G11 on the TigerDirect AX3U1600C4G11-SD modules means that the timing is 11-11-11-??

Anyway, I am thinking about getting another pair of Adata 4GB modules, but from a different vendor (Newegg). Same manufacturer, identical looking other than the color of the heat spreader, and the model number is slightly different: AX3U1600C4G9-DR
Newegg's specs: Timing 9-9-9-24; Cas Latency 9; Voltage 1.5V

Would I be asking for trouble by trying to have two slightly different memory modules even by the same manufacturer?

Karsten75 · Dec 15, 2014

At best the memory will run at the speed of the slowest RAM. At worst it won't boot. In desktops it's sometimes possible to fiddle with BIOS and make it work, laptops in my experience are more fiddly.

I've learned from past expensive lessons to buy memory in kits and upgrade by doing complete swaps. Not always cost effective.

Tradesman1 · Dec 15, 2014

Yep best bet is a set of the complete amount you want, any time you mix packages (even of the same exact model) it can be problematic. I'f they will play, what they will and can run at, depends on you and how you set them up, I've often taken mixed sticks say 1333 and 1600 or 1866 and 2133 and get them set to run at the higher freq, this bit of they will only run at the lowest spec freq is a myth

Zorba Greekthe · Dec 15, 2014

Karsten75 :

Ugh, wish I had asked this BEFORE placing the darn order! Well, I may be out of a restocking fee and return postage then.

So there's no possibility of causing any permanent damage to the system or anything like that if I try to boot it up, is there?

Tradesman1 · Dec 15, 2014

Hmmm, already ordered, your call, unfortunately think the ADAYTA sticks are generally all in a sealed semi perforated clamshell type casing, so if opened - everybody knows it, could simply return them and pay the restocking, or can try them, I've had good luck in getting sticks to play together and am willing to help try if you go that route. Have been working with some of their sets and would guess we could get them running at about 10-10-10-28 with 1.55 to 1.6 DRAM voltage (all is safe)....If you decide to try and have problems, give a shout

Zorba Greekthe · Dec 15, 2014

Tradesman1 :

Thanks, I will take you up on your generous offer if needed. This is a non-gaming system, so I doubt that running the memory on the slowest speed is going to make any noticeable difference...my main concern is system stability, just wanted the extra memory for my Google Chrome massive multi-tabbed browsing habits.

Zorba Greekthe · Dec 19, 2014

S-weeeeet! All 4 sticks are running fine so far, could be a placebo effect but I could swear the system feels a little snappier and booted up faster now that I have 16GB instead of 8GB. I will turn off the paging file, only had it set to a fixed 2GB size before anyway.

CPU-Z shows that it's running at 1300MHz ... should I bother going into BIOS to manually increase it to ADATA's spec of 1600MHz or should I leave it well alone? Was thinking that with my non-gaming and CPU non-intensive usage that extra 300MHz probably won't make any noticeable difference and I wouldn't want to risk any hiccups for that anyhow...

Tradesman1 · Dec 19, 2014

Give it a try, at worse you might need a bit of extra voltage to the DRAM if they are balky at 1600, simply add +0.05 to the DRAM voltage - i.e. if 1.5 sticks change to 1.55

Zorba Greekthe · Dec 20, 2014

Tradesman1 :

huh, went through BIOS and it shows the computer is only recognizing one pair of 4GB sticks as 1600 and the other one as 1333 even though both are listed by ADATA as 1600. So I used the AI Tweaker to change the DRAM "Target Frequency" to 1600, rebooted, but CPU-Z still shows 1333 speed.

Oh well, no biggie. Googled the difference between the two memory speeds and the consensus is that for real world usage, especially outside of gaming and doing stuff like Photoshop, there really isn't any. Guess I'll just leave it alone for now...

Tradesman1 · Dec 20, 2014

What does it show next to frequency in the memory tab of CPU-Z? Should be 800 as it's DDR (DOUBLE data rate) (800 x 2 = 1600) if you are seeing 1333 for 1 and 1600 for the other you are probably looking at the SPD data, not what it is running at. The frequency pane is what all the sticks are actually running at (800=1600) or if it shows 667 then all are at 1333

Zorba Greekthe · Dec 20, 2014

Tradesman1 :

On the memory tab it says DRAM Frequency: 676.8 MHz

I was seeing 1333 for 2 of the sticks, and 1600 for the other 2 sticks, in my BIOS not in CPU-Z.

The SPD tab of CPU-Z seems to be giving 4 different Frequency readings for each DIMM, oddly enough.

Here's a link to the CPU-Z report I printed out:
https://www.dropbox.com/s/9gmgx4uc6xh7q2x/CPUID%20CPU-Z?dl=0

Tradesman1 · Dec 21, 2014

Have you tried manually setting them to 1600 w/ the above mentioned timings/setup? The data in the SPD tab is simply that, data about the sticks, the BIOS takes that in and tries to set the sticks to what it is programmed to be the 'best match', here it decided on 1333. However you can manually set them to other timings and freqs

Zorba Greekthe · Dec 22, 2014

Tradesman1 :

Right now the UEFI home screen is reading DIMM 2 & 4 as "Undefined 4096MB 1600MHz" and DIMM 1 & 2 as "A-DATA 4096MB 1333MHz." Don't know if that's an incorrect reading on the part of the motherboard, or the fault of one of the pairs of 4GB sticks.

Strangely enough, today when I re-entered the DRAM Frequency to the next step up on their pop-up scroll menu to 1624MHz in the AI Tweaker Advanced Mode screen, it actually stuck! So now CPU-Z is showing the 4 sticks running at 1624MHz...keeping my fingers crossed that this will not cause any system instability or weirdness since I am technically overclocking the memory...

Didn't change the timings because I didn't see any options to do so. Am assuming that it will just go with whatever the slowest timing is...

Tradesman1 · Dec 22, 2014

Depends on your BIOS, it may be to the slowest or to what the BIOS is programmed for as 'best', can see the timings in CPU-Z in the memory tab

TechsavvyAMD · Dec 23, 2014

For two RAMs to be worked synchronously,speed,brand,size should be same...........it will work as dual memory technology........
timing and latency does not matter in this case.......................

Zorba Greekthe · Dec 28, 2014

Well, one week later my system is still running fast and stable, so I guess I will let the inexplicable memory readings in BIOS and CPU-Z stand as is.

Also strange is that it suddenly boots significantly faster...about 2-3 seconds before the 4 Windows color blocks come together on the bootup screen! I must've inadvertently done something while digging around the BIOS, thought that Fast Boot was already enabled though.

All good, though...thanks for the help, everyone!

Tradesman1 · Dec 28, 2014

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Can I use DDR3 modules with different timings and Cas latency?

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