7600 cl34 is stable at 1.45V VDD/VDDQ/VDDIO (or even 1.4V), but 7800+ is only somewhat stable at 1.6-1.65V VDD? What is the correlation between voltage and frequency (not including timings)?
I bought theese parts when ram prices were at least x2, so I've got not many choices:
- RAM: XPG Lancer White AX5U6400C3216G-DTLABWH Single Rank Hynix 16 Gb A-die (Canopus / 15 nm) / 1 die H5CG48AEBDX018 chips
- MB: ROG STRIX B850-I GAMING WIFI – this ITX motherboard should be able to handle 8000 ram
- CPU: 9800x3d
Ram EXPO 3200 MHz / 32-39-39-89-128 / 1,40V – was not stable even at 1.3 VSOC in 1:1 mode so I decided to go for 8000 MT.
I've tried Buildzoid 8000 timings (from this, this and this videos) at 1.5V – they were not stable in minutes of Tm5, then applied integrated ASUS profile for SR Hynix 8000: 34-48-48-48-38 with 1.55 VDD/VDDQ, 1.45 VDDIO, 1.1 VDDP (are theese safe???), changed tras to 127 and noticed that I was able to pass 10 minutes in TM5. Then I've tried to change voltages in different combinations 1.45-1.55 VDDQ, 1.05-1.15 VDDP – nothing changed. Then I pushed VDD to 1.6V – got error after 2h of Tm5. That was something. I noticed that everything below 1.6V was unstable in minutes in Tm5.
I changed primary, secondary timings to lowest values I know to find lowest voltage possible – nothing changed even at 40cl and 1.6V. I throught maybe temp is too high (58 max) so lowered trfc to 960 and thefi to 32768 – nope, not stable. Added slim 120 on top of ram modules – nothing really changed even in temps, those radiators are really bad.
Then I reset the profile again to defaults with 34cl, 470 trfc, 65565 trefi, pushed VDD to 1.65 with all fans at max and was able to pass 3h of TM5 with 62 degrees max. wtf… But then I failed in VT5 in 30 minutes with temps at 49. double wtf. And the worst thing – errors were after 1-2h, even 2.5h into tm5 or VT3 tests, so they looked like stable at start, but they were not.
I thought maybe something in my build can't handle 8000, changed to 7800 – unstable. But at 7600 it was rock solid, and even at normal VDD at 1.45 I passed 3h Tm5, 7h VT3, 11h Prime95 Large. Even tried 1.4 VDD/VDDQ/VDDIO – 10 minutes of tm5 OK, I will be cheking this one later today.
Also (maybe its not related, but strange) I was not able to pass stability tests with easy Buildzoid timings at 6200 at 1:1. At first I thought maybe my IMC was so bad it cant handle 3100 UCLK, but then I found this Buildzoid 6200 cl30 video and it was stable…
I know that most voltage sensitive things in DDR5 Hynuix A-Die is CL and you don't need 1.65VDD to get 8000 if you are not pushing below 36. But for me everything after 7800+ was instantly unstable below 1.6VDD, still perfectly stable at 7600 1.45VDD. Could plese someone explain me what is going on, and what am I missing here? What can I change to get 8000 stable? Or should I dump this idea and live with 7600/6200 instead?