Memory Kits and Overclocking
When we set out to purchase the components for our system, we must be confident that all the parts we are buying are compatible. Whilst experienced users may navigate this process with confidence and despite the seeming simplicity, there might be some nuances that aren't so obvious that can influence our decisions depending on our level of experience. Motherboard vendors employ what's known as the QVL (Qualified Vendor List) which gives users a list of components that have been verified as tested on a particular motherboard.
QVL-validated kits come with either an XMP or EXPO profile. These profiles serve to activate the specific parameters assigned by the memory vendor. The profile information is stored in what is known as an SPD table on the memory module. The SPD (Serial Presence Detect) is a small chip on the memory module that holds crucial data provided by the manufacturer. Vendors utilize a designated section or "table" to store the XMP or EXPO profile data.
AMD EXPO™ Technology - AMD Ryzen™ 7000 Series Processors | AMD
Intel® Extreme Memory Profile (Intel® XMP) and Overclock RAM
XMP/EXPO undergoes validation by the memory vendor. The process involves comprehensive testing on a sample of motherboards within their possession, and sometimes through machine testing depending on the memory vendor. Motherboard manufacturers also conduct their qualification processes to determine what's possible on each SKU. What memory kits are validated on a particular SKU depends on the DRAM trace layout and topology, the quality of components used as well as limitations imposed by the CPU memory controller.
It's crucial to note some key considerations when opting for a memory kit:
XMP/EXPO is Overclocking
Using XMP/EXPO means deviating from default stock settings. Any memory configuration different from JEDEC or processor specs is considered an overclock. JEDEC (Joint Electron Device Engineering Council) standard is the set parameters to which the memory IC manufacturer adheres and ensures the memory operates.
Pre-overclocked, but not assured overclocking
Contrary to assumptions, XMP/EXPO doesn't ensure automatic overclocking. Tighter timings or higher frequencies may require manual adjustments for stability. Overclocking cannot be assured due to variance between parts when run outside manufacture specifications. XMP/EXPO success also greatly depends on the processor's Integrated Memory Controller (IMC) capabilities.
What is the difference between XMP I, 2 and Tweaked?
XMP/EXPO I - This is the validated board profile. Every time a board is validated with a particular memory kit, the memory vendor and ASUS use this profile to validate the kit for the QVL.
XMP/EXPO II - This is the default DIMM profile from the memory vendor and contains sub-timings stored within the SPD EEPROM of the memory module.
XMP/EXPO Tweaked - This is the fastest profile and contains various tuned sub-timings and memory parameters.
Increase Success Probability
For better success in achieving "plug and play" overclocking, consider memory kits that are one to three frequency bins below the motherboard's maximum qualification on the QVL. The higher the frequency and tighter the timings, the more likely manual tuning might be needed to adjust for signal variance between parts—success with memory kits at or near the top of the QVL validation table depends largely on the quality of the CPU memory controller.
Don't Combine or Mix Kits!
Combining and mixing memory kits isn't supported by memory or motherboard vendors. If you combine memory kits, the overclocked settings in which the kit is validated for XMP/EXPO are no longer valid. Purchase a single kit validated for the density and frequency you are trying to run. This is because memory vendors bin and validate the memory kit in the density in which it is sold. Whether we combine a kit with the same part number, frequency, timings or voltage the advice remains the same.
For more insight into the challenges faced when combining kits you can refer to this article Don't Combine Memory Kits! The Meat & Potatoes Overview
Key Points on Why Not to Combine Memory Kits:
Mismatched Timings and Density:
Troubleshooting Challenges:
Time-Consuming Tuning Process:
Recommendation for Simplicity:
AEMP & AEMP II
- AEMP or ASUS Enhanced Memory Profile functionality is exclusive to non-XMP memory modules.
- AEMP is currently available on all DDR5-based Z690 and Z790 motherboards.
- Memory kits with an XMP profile will not be compatible with AEMP or AEMP II.
- Users can easily identify whether their memory modules support XMP through the ASUS SPD Information within the UEFI Tools Menu.
- ASUS AEMP unlocks the onboard memory module PMIC (Power Management Integrated Circuit) for non-XMP memory kits, enabling them to be overclocked.
AEMP Profiles
- AEMP I tightens the memory timings to improve memory latency.
- AEMP II increases the memory operating frequency to improve the memory bandwidth.
AEMP is still overclocking
Despite being more conservative than the majority of XMP DDR5-based memory kits, ASUS Enhanced Memory Profiles still exceed the DRAM manufacturer's tolerances and are considered an overclock. Whilst new AEMP II firmware allows for mixing different brand memory ICs (assuming they are the same capacity), success still depends on the strength of the CPU memory controller and the operating range of the memory modules when running out of specification.
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