Published March 31, 2026 - Updated April 1, 2026 - By Xilly
Easy DDR5 Timings for AMD
Unlock hidden performance in your AMD system. From physical slot placement to advanced BIOS sub-timings, this guide breaks down the exact DDR5 optimization process we’ve used on over 10,000 high-end gaming PCs. No fluff, just pure frames.
RAM Optimization Guide · DDR5 AMD
We've optimized over 10,000 PCs. DDR5 timing optimization is one of the single biggest performance gains we deliver to competitive clients - and most people have no idea where to start. This is the simplified process we follow. No fluff. No guessing. Follow this and your RAM will perform better in every gaming workload.
Step 1: Check Your RAM Slot Placement
Before touching anything in BIOS, open Task Manager and hover over Slots Used. Your sticks need to be in slots 2 and 4. This is correct on ASUS and 99% of motherboards.
If you're running four sticks, pull two of them out and put the remaining pair in slots 2 and 4. Four sticks of DDR5 is extremely hard on the memory controller and will prevent you from achieving stable overclocked timings.
Always run two sticks: 2×16GB, 2×24GB, 2×32GB,
or 2×48GB. If you genuinely need more capacity for workstation tasks,
this guide may not apply to your use case.
Step 2: Update Your BIOS First
Do not skip this. AMD's AGESA microcode updates directly improve memory training behavior, stability at tighter timings, and UCLK ratio handling. An outdated BIOS will undermine everything in this guide.
We have a guide on how to update your BIOS without a USB stick on the Xilly YouTube channel. Watch that first, update your BIOS, then come back here.
Step 3: Identify Your Memory Die
Download HWiNFO64, launch it in full mode, click the memory chip icon, and look at the top for your die type. This determines which timing values apply to you.
32GB kits with CL26 or CL28 EXPO profiles. Can go lower on tRFC and tRRDL. Best results overall.
Most 48GB kits. Some 32GB kits with CL30-38 EXPO at 6000, or CL32-40 at 6400. Needs tRFC slightly higher, tRRDL slightly looser.
Do not touch primaries or tRFC. Safe sub-timing and refresh changes only. See the Micron & Samsung section below.
Same restrictions as Micron. Even small tRFC changes will cause a no-boot. See the Micron & Samsung section below.
If you can, zip-tie a case fan alongside your AIO tubes and point it directly at your RAM sticks. It makes a real difference on tRFC and tREFI stability - both are extremely temperature sensitive.
If you're on 64GB or 96GB with RGB: turn RGB off before you do anything. High-capacity RGB sticks run hot and will cause instability when you increase tREFI or tighten tRFC.
Step 4: BIOS Settings - Hynix A-die & M-die
Restart and spam Delete to enter BIOS. Go to Advanced Mode → AI Tweaker (ASUS) or equivalent on your board.
2000 MHz.
CPU bin quality determines max stable FCLK - some chips won't do 2067 cleanly.
If you're running dual rank kits (2×48GB or some 2×32GB),
leave tCL, tRCDRD, and tRP at their EXPO defaults. Everything else
in this guide is safe to apply.
32767 instead. tREFI is extremely temperature sensitive - higher values improve frame consistency but require adequate cooling.12 - the safer value for both.Press F10, save, and boot.
If Your PC Doesn't Boot After These Changes
Don't panic. This is normal for some systems. DDR5 timing changes require your memory controller to retrain, and some boards will fail to POST on the first attempt or two.
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1Wait up to 90 seconds
Some boards will self-correct and retry automatically, or POST to a safe mode message saying "overclocking failed." Give it time before assuming it's stuck.
-
2Clear CMOS if still no display
Shut down fully at the PSU switch. Find the CMOS button on your rear I/O panel (most modern boards have one) or locate the CMOS jumper on the board itself. Press and hold for 30 seconds. Power back on - BIOS will reset to defaults.
-
3Reapply settings one section at a time
Re-enter BIOS and apply the sections from this guide sequentially. This isolates which setting caused the failure.
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4If you fail a second time
Most common causes: tRFC is too low for your specific die (try increasing by
+32and test again), or the primary timings don't work with your kit - in that case try raising DRAM VDDQ to1.45Vor leave primaries on EXPO/XMP defaults.
Step 5: Post-Boot Verification in HWiNFO64
Once back in Windows, open HWiNFO64 and navigate to the memory timings view. Confirm all your values applied correctly.
Micron & Samsung: Safe Tuning Only
Do not touch the primaries. Do not touch tRFC. Even small changes on these dies will give you a no-boot almost every time. The tuning below is what's safe.
If you don't boot after applying these, clear CMOS and start over with just the speed and FCLK changes. If Micron or Samsung is holding back your performance, the upgrade path is Hynix A-die or M-die - the difference is significant.
Frequently Asked Questions
What DDR5 memory die is best for overclocking on AMD?
Hynix is the best DDR5 die for overclocking on AMD AM5. Within Hynix, A-die (32GB kits, CL26/CL28 EXPO) can achieve lower tRFC and tRRDL values. M-die (most 48GB kits, CL30-38 EXPO at 6000) needs slightly higher tRFC and looser tRRDL but still overclocks well. Micron and Samsung offer very limited tuning - do not touch their primaries or tRFC.
Why DDR5-6000 and not higher on AMD?
At 6000 MT/s, the memory controller runs UCLK=MEMCLK in a
true 1:1 ratio, giving maximum bandwidth with minimum latency. Going above 6000 drops
UCLK to divide-by-2 mode, which significantly hurts gaming performance. The only
exception is targeting 7800-8000 MT/s which can exit divide-by-2, but requires
significantly more tuning effort, SOC voltage control, and FCLK validation.
Should I run 2 or 4 sticks of DDR5?
Always run two sticks for gaming optimization. Four sticks puts extreme stress on the
AMD memory controller, limits overclocking headroom, and often prevents stable 1:1
UCLK ratios. Run 2×16GB, 2×24GB, 2×32GB, or
2×48GB depending on your needs.
What is tREFI and why does it matter for gaming?
tREFI controls how often your RAM pauses to refresh its stored data. Increasing it
reduces refresh interruptions, directly improving frame consistency and 1% lows.
With a fan pointed at your sticks, 65535 is stable. Without RAM
cooling, use 32767. Both tREFI and tRFC are extremely temperature
sensitive - this is why dedicated RAM airflow matters.
What do I do if my PC won't boot after changing timings?
Wait up to 90 seconds - some boards self-correct. If still no display, clear CMOS
(rear I/O button or jumper on the board), re-enter BIOS, and reapply settings one
section at a time. If you fail again, the most common causes are tRFC set too low
for your die (increase by +32) or primary timings incompatible with
your specific kit.
What voltages should I set for DDR5 on AMD?
For Hynix at DDR5-6000: CPU SOC 1.25V, CPU VDDIO/MC 1.4V
(match your DRAM VDDQ), DRAM VDDQ/VDD 1.4V. Micron and Samsung kits
do not need voltage changes for the safe tuning they support.
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