Question Corsair XMS3 Running at 1333Mhz

Sep 25, 2020
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So I noticed the other day my XMS3 RAM is only running at 1333Mhz when it should be running at 1600Mhz. I have 3x 4GB sticks and XMP will work with two but when I put the third in, the system won't even post.

I've tried:
Setting Multiplier to 16.00 (Constant Beeps)

Setting Timings and Voltage to 9-9-9-24 and 1.65v respectively (Constant Beeps)

Choosing XMP Profile (No Post, Computer Restarts Infinitely)

Any help greatly appreciated!
 

PC Tailor

Judicious
Ambassador
Presumably you have bought the RAM separately?

If so, mixed RAM modules are not guaranteed compatibility, and mixing with 3 DIMMs can make it even more difficult for XMP profiles to work correctly.

Does ANY RAM module in a third slot not work?
 
Sep 25, 2020
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Presumably you have bought the RAM separately?

If so, mixed RAM modules are not guaranteed compatibility, and mixing with 3 DIMMs can make it even more difficult for XMP profiles to work correctly.

Does ANY RAM module in a third slot not work?
All DIMMS are Corsair XMS3 4GB 1600Mhz, 11-11-11-30 1.50V (Tried those settings, don't work either). The only difference I can see on the label is two sticks are V2.13 and the other is V7.13. Could there be subtle differences in the two versions which would stop XMP from working?
 

jasonf2

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Oct 11, 2015
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What is your cpu? Some of the AMDs don't like odd timings. Try a 10,10,10,24. Beyond that RAM is a finicky overclock sometimes. Your clock is where it is because that is where corsair set the SPD which is kind of a guaranteed safe clock. Regardless of the memory sometimes the motherboard simply cannot handle it and every stick varies somewhat on what it can actually do which is why SPD is typically less than advertised clocks on high end RAM. XMP isn't something that "works" it is more of a built in overclock profile. So if the module isn't able to take it or your motherboard isn't there turning on XMP isn't much different than setting up your timings and clock to an unstable level. Also mix and matching sticks with RAM overclocks is setting yourself up for disappointment. It is also important to understand that sometimes with RAM overclocking it may have no real performance gain if you have to mess with timings too hard. Those numbers are in essence delays counted in clock cycles. So if you are having to up the delay by two clock cycles to stabilize the system you are losing ~20% to gain ~20% clock frequency for no net gain and increased power consumption while you have to up your voltage. Serious overclockers will often buy multiple sets of memory and test out each stick and bin the best performing together but they are all going to be the same. If you have two different version numbers on your sticks they are not the same and performance could be all over the place.
 
All DIMMS are Corsair XMS3 4GB 1600Mhz, 11-11-11-30 1.50V (Tried those settings, don't work either). The only difference I can see on the label is two sticks are V2.13 and the other is V7.13. Could there be subtle differences in the two versions which would stop XMP from working?
That's still called mixing and matching even if you bought the same model at different times.

That's why you see them sold in kits... they're tested working together. Even with similar model modules you may encounter instability or compatibility problems if bought separately.

Also, your 3 modules config is suboptimal... your 2x4gb is running in dual channel and your other 4gb in single channel.
 
Sep 25, 2020
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What is your cpu? Some of the AMDs don't like odd timings. Try a 10,10,10,24.
I'm running an i5 3570 on a Gigabyte Z77X-UD3H. I've tried those timings and it still won't have any of it. Beginning to think maybe 12GB at 1333Mhz is better than 8GB at 1600Mhz anyway. I've heard it passed around the forums that RAM speed makes a marginal difference. Just 1333 still sounds slow these days!
 

PC Tailor

Judicious
Ambassador
All DIMMS are Corsair XMS3 4GB 1600Mhz, 11-11-11-30 1.50V (Tried those settings, don't work either). The only difference I can see on the label is two sticks are V2.13 and the other is V7.13. Could there be subtle differences in the two versions which would stop XMP from working?
Doesn't matter - as @ChumP has said. They're sold in packs for a reason. I go a little bit more detail on it in point 4 in this guide. Someone also asks for more detail on it in the comments and myself and Mod go through more detail.
 

jasonf2

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Oct 11, 2015
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I'm running an i5 3570 on a Gigabyte Z77X-UD3H. I've tried those timings and it still won't have any of it. Beginning to think maybe 12GB at 1333Mhz is better than 8GB at 1600Mhz anyway. I've heard it passed around the forums that RAM speed makes a marginal difference. Just 1333 still sounds slow these days!
Clocking anything is more of an art than a science. It is really about tweaking your system to what it can actually do rather than safety margined specs. Personally looking at the stock SPD timings and your target clock I have a feeling that someone that really knows what they are doing and has patience can probably get the clock up a couple hundred mhz. But performance wise it is going to be a wash by the time timings are adjusted. Although I have done it a number of times over the years (some chips beg for it) I am not a huge fan of overclocking. I would rather have a stable machine 100% of the time than a slightly faster machine that is stable 99% of the time. With that being said an overclock is not intrinsically unstable, but it takes time to prove stability with every potentially stable setting that most people don't take. If you are going to overclock anything you really need to test and retest. Just because it posts doesn't mean it is stable.
If your modules are running at 9-9-9-24 @ 1333 which looks to be the SPD timings don't feel that bad though. If you look at what I am running (DDR4 PC4-28800 tested to 3600 mhz) its SPD sets at 2133 MHz at 15-15-15-36 timings. So from rough numbers on the SPD level your ram with its timings is probably on par with mine. This is because while my clock is ~38% faster my timings are roughly ~40% more delayed. The only real difference is that I have quite a bit more overclock headroom.
Best of luck!
 

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