Question What Ram Do I Use and are two identical stick same as kit?

[fedefrasis]

Hello
Hi, im bulding this system ina few days (only the case is left to ship)
Ryzen 9800X3D
Asus X870E-E Gaming WiFi
RTX 5080

I originally bought 64gb ddr5 rams CMK64GX5M2B6000Z30 by Corsair

Problem is, QVL for motherboard lists a close CMK64GX5M2B6000Z28(Ver 5.43.01) but not mine which is the z30 / cl30
Is this due to them not testing every variant and mine will work or do i specifically needed to have bought that SKU z28?

there is a z30 corsair 2x32 6000 listed but its a different kind of ram with rgb and higher heatsinks

So then i bought these XPG rams ax5u6000c3032gslabrbk from adata. As far as i can tell they are IDENTICAL to the black ones nonrgb (they didnt have non rgb, i hate rgb) which are in the qvl

Is there any difference between a prebought kit and two identical stick bought separately?
Is there any quality difference? Which do i use? Thanks!

 

[dwd999]

Most memory manufacturers say that only prebought kits should be used. So don't be surprise if two sticks bought separately don't work.

 

[fedefrasis]

Most memory manufacturers say that only prebought kits should be used. So don't be surprise if two sticks bought separately don't work.

so which do i use

 

[dwd999]

so which do i use

If you have them already you can try them but don't be surprised if the don't work. If they do work, fine. If they don't work then return them and buy a manufacturer certified matching set.

 

[Misgar]

Is this due to them not testing every variant and mine will work

Manufacturers don't check every single variant of RAM in their motherboards.

There's a good chance both pairs will work at JEDEC speed (typically 4800MT/s or 5200MT/s).

Whether or not a Ryzen CPU will also work at 6000MT/s with Intel XMP settings remains to be seen.

In many instances, a Ryzen will boot quite happily at XMP 6000MT/s, but ideally you need a kit with EXPO settings, specifically designed for AMD CPUs.

If neither of your kits boots up and is stable at 6000MT/s, it may be possible to manually tweak a few timings to achieve stability. The trick is knowing what settings to change and how to test for stability.

If there is a time window on returning the RAM, e.g. 30 days and you're getting close to the deadline, it would be better to return all the RAM that does not come with EXPO timings.

Most desktop RAM comes with Intel XMP (Extreme Memory Profile) overclock settings. Some kits come with AMD EXPO settings. The differences are subtle, but can be important if you've bought a particularly bad combination of mobo, CPU and RAM.

When you build your computer, leave the BIOS settings for memory at the default JEDEC speed, e.g. 4800/5200MT/s and install Windows. If the system appears to be stable, you can go back into the BIOS and switch on XMP (or EXPO).

With XMP enabled, your RAM speed will increase from 4800/5200 JEDEC to 6000MT/s XMP/EXPO.

If the system seems stable at 6000MT/s, download a copy of MemTest86, burn the ISO to a USB memory and boot up into MemTest86 from USB.

This completely bypasses Windows and allows MemTest86 to thoroughly test your RAM, taking several hours to complete the task.

If MemTest86 gives a 100% clean bill of health, breathe a sigh of relief., but if you get even one error in MemTest86, your RAM is not stable.

You then have the choice of manually tweaking some settings and continuing to test until the system is stable, or returning the RAM and buying a kit specifically designed for AMD CPUs (with EXPO timings).

 

[Misgar]

Is there any difference between a prebought kit and two identical stick bought separately?

No two kits of RAM can be guaranteed to be identical, even if they have exactly the same part number. It's possible/probable that two "identical" kits will contain memory chips from different bins and hence will not be precisely matched.

People discover this fact when they add a second pair of DIMMs with the same part number, to increase the amount of RAM in the computer.

Apart from the fact you may have to reduce the clock frequency with 4 DIMMs fitted, the fact the two pairs are not matched can lead to instability.

If you think you might need 4 DIMMs at some time in the future, try instead to buy 2 DIMMs of larger capacity. 2 DIMMs usually overclock faster than 4 DIMMs.

If you cannot obtain the desired capacity with only 2 DIMMs, buy a kit containing 4 matched DIMMs now, not two kits of 2 DIMMs at different times, which will then be unmatched.

There are always exceptions to the rule. Some people never have problems mixing RAM. Other people start tearing their hair out in frustration.

 

[bill001g]

There are a number of factory tour videos on youtube that show them manufacturing memory sticks. The machines are testing every single chip that goes on a stick and matching similar ones into groups. Then after the sticks are made they test again and group stick that have closely matched numbers into kits.

They of course are not just doing this to increase the stability they will take the very best sticks out and sell them for far more. This is why you can not really overclock stuff much anymore the factory has already checked and remove the devices that can be easily overclocked.