There's this guide: MemTestHelper/DDR4 OC Guide.md at oc-guide · integralfx/MemTestHelper
While it's written for DDR4, and the specific timing recommendations don't really apply, the principle and order of tightening timings remains the same (lower one timing at a time, test stability, rinse and repeat)
Here's what's changed in terms of DDR5 OC on Intel CPUs:
- tCL needs to be a multiple of the gear ratio, in gear 2 that means it has to be an even number, while gear 4 means it needs to be a multiple of 4
- tRCD and tRP are now separate timings
- tREFI can now run as high as 262143, this is the only timing where higher = better.
- Tertiary timings for Intel on DDR5 are now at minimum 7, rather than 4.
- Due to the increased number of banks on DDR5, _dg timings have a significant impact on performance, _sg timings doesn't make the same kind of difference.
- tRFCpb / tRFCsb is a new timing, which refreshes a single bank, this allows the CPU to still access memory while data is being refreshed. Tightening it works similarly to tRFC.
- Some testmem5 presets work better than others, ironically enough I've found 1usmus_v3 to work quite well.
- tWR is controlled by tWRPRE and tWRPDEN, if you want a formula: tWR = tWRPDEN - (tCWL + 8)
- tWTR_S and tWTR_L are controlled by tWRRD_dg and tWRRD_sg respectively. tWRRD_dg and _sg can have a significant impact on performance, and they can often only tighten 2-6 ticks from stock timings.
For the Hynix ICs you're using, here are my suggestions as a starting point:
tCL 11 ns
tRCD 13 ns
tRP 13 ns
tRAS 13 ns
tRFC 130 ns
tRFCpb 90 ns
Note that I listed these values in terms of absolute time, and you'll have to multiply them by the actual frequency to get a suggested timing.
Example: tCL at DDR5-5600
DDR5-5600 has an actual frequency of 2.8 GHz
tCL is suggested 11 ns
tCL in ticks = 11 ns * 2.8 GHz = 30.8
Rounded up to the nearest multiple of 2, we get tCL 32 as a starting point.
For the rest of the timings, we then get
I use GigaHertz here because Giga (10^9) complements nano (10^-9) so that I don't need to multiply or divide by 1000
Hope this is at least somewhat helpful to you.