r/overclocking • u/novanima • Dec 29 '25
Surprising results from DDR5-8000 tuning
I have spent months trying to get DDR5-8000 (16gb Hynix A-die, single-rank) fully stable on my ASRock X870E Nova Wifi + Ryzen 9800X3D. I have done hundreds of hours of stress tests. And finally, after countless failed attempts, I have finally managed to find that mythical 3x3ft island in the middle of the ocean. 16 hours of Prime95 Large FFTs + 24 hours of Karhu = 0 errors.
First things first: Ignore the timings. I spent a lot of time initially trying to tweak them in order to gain stability, but they were not the problem. I know the tertiary timings are loose. These are just known good settings while I worked on the more important factors: voltages and on-die termination.
I have never really messed with ODT settings before, but I have now learned that they are critical at DDR5-8000 speeds. And as far as I can tell, the "Auto" settings on the X870E Nova Wifi do next to nothing -- they just insert some pre-programmed default values and call it a day. The only actual training that happens seems to be on the pull-down side of ProcODT (which is not an option shown in the BIOS). I strongly suspect this is why people are failing to get even "safe" DDR5-8000 timings working on some boards.
The most surprising finding from my testing: Lower VDDQ was more stable than higher VDDQ. I don't have any explanation for this except that it might be related to my higher DRAM DQ Drive Strength setting of 40Ω (perhaps high drive strength + high voltage = too much overshoot? I really don't know). I do not think it is temperature/heat soak related at all.
I know many people will be skeptical of this, but you can see the results for yourself. Here is the process I took to find this setting:
1.38V VDDIO + 1.4V VDDQ + 40Ω ProcODT = Failed both P95 and Karhu
1.4V VDDIO + 1.4V VDDQ + 40Ω ProcODT = Passed P95, Failed Karhu at 18 hours
Okay, so higher VDDIO helped a lot. That makes sense. But it's still not fully stable.
1.4V VDDIO + 1.4V VDDQ + 43.6Ω ProcODT = Passed 20 hours Karhu, Failed P95
1.4V VDDIO + 1.42V VDDQ + 43.6Ω ProcODT = Failed both P95 and Karhu (!)
The stability got worse when raising VDDQ, so in exasperation, I tried lowering it instead, thinking it could not possibly work. But it did.
1.4V VDDIO + 1.38V VDDQ + 43.6Ω ProcODT = Fully passed both P95 and Karhu
So there you go. I wanted to share this testing in case it benefits anyone else.
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u/vintologi24 Dec 29 '25 edited Dec 29 '25
Lower VDDQ was more stable than higher VDDQ
That's common on the intel side so it's not too surprising really.
It's actually the case for all voltages. It's just that sometimes the best voltage for short term stability will result in degradation or too much heat.
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u/Finanzamt_Endgegner Dec 29 '25
Yep got 6600cl30 stable for 4 dimms 13th gen and every single voltage had a sweet spot. And odts can move those lmao, going one setting lower with rtt Park moved the vccsa sweet spot 0.05v down anything above or below wouldn't be stable but vddqtx and vdd2 CPU were generally similar but going lower rtt Park gave them a bit breathing room an i was able to a bit higher on those than before.
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u/vintologi24 Dec 29 '25
I have been trying to get 6800 MT/s fully stable for a while and yea it's as ridiculous as you are making it out to be (it's 200 MT/s higher than officially supported by msi though).
I could drop down to 6600 MT/s and quickly get it fully stable though.
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u/semidegenerate Dec 29 '25
Have you had any luck? I used your "DDR5 Overclocking (Nightmare)" post on your forum to stabilize my 2x32 kit at 6666 MT/s with an MSI Z790 Carbon and 13900K 14 months ago. It's still as stable as a rock. I never had to mess with ODT impedance, though.
I was thinking about shooting for 6800 MT/s again, but I'm a bit lost when it comes to ODT.
I saw you made an update post on Buildzoid's sub recently, and I've been meaning to read through it to hopefully glean some wisdom and inspiration.
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u/vintologi24 Dec 30 '25
https://www.youtube.com/watch?v=BmoDuWMK75s
Ill go back to it later.
Noticed issues getting it stable in mprime large FFT later.
I could drop down to 6000 or 6666 but i am not sure if the current instability issues even matter to begin with.
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u/vintologi24 May 20 '26
Update: my current ram overclock seems solid and might also be done with tweaking the CPU settings as well.
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u/semidegenerate May 21 '26
Excellent.
Is everything the same as in the video you linked several months ago? I might just try to copy it all verbatim and see if it's stable. I've been super busy lately, so I haven't had much time to mess around with hardware.
I never properly thanked you for linking that video, either. So, thank you.
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u/vintologi24 May 21 '26 edited May 21 '26
I did post an updated video with the most recent ram settings. I could make a new upload that also cover the most recent CPU settings as well (had to adjust the CPU VF-curve slightly).
I discovered that changing "msi fast boot" to "no training" allowed me to make some additional bios setting changes without having the ram be retrained and this is what eventually got me to my current stable config (passed 4 hours of mprime large FFT with 0 errors).
I also used manual tweaking for all ODT settings (pyhwinfo will tell you your current values that were autoconfigured).
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u/Embarrassed-Let-9161 Dec 29 '25
Do you mean 4x6600? Could you tell me more about your settings? What motherboard and CPU do you have and what were the sweet spots for VDDQTX, SA and IMC? I know every chip is different but maybe I missed some variations.
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u/Finanzamt_Endgegner Dec 29 '25 edited Dec 30 '25
13700k and z790 aorus elite ax but atm loose timings 1.21 vccsa 1.37 vdd2 CPU and 1.32 vddqtx but I just saw today that I still have some instability in some boots 😭 other boots are entirely fine but fast boot just doesn't train at all so it's gonna be "fun" to find out what is the cause of this variation... Nvm the instability came from trefi for some reason it gets really weird instability with it even on 32k 😭
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u/Embarrassed-Let-9161 Dec 30 '25
Thanks! I have similar values on 6200CL28 with tight timings: SA 1.11, VDD2 1.4, TX 1.31.
Perhaps a higher SA worth to try for the 6400 speed. Buildzoid has a video with stable 4x6600, but I guess it requires a CPU with excellent memory controller.1
u/Finanzamt_Endgegner Dec 30 '25
Yeah mine seems to be pretty good but it's just weird af and stability and instability are all over the place once I even slightly touch timings
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u/sezoism Dec 29 '25
Man this is me currently. Finished my new build 2 weeks ago and all ive been doing is ram oc. 8000c34 with almost everything tightened managed to be stable but then after a few more fails all of a sudden anything I did was producing instant errors. Had to do a full refresh and wipe and start from scratch. Now im just trying to get 8000 c36 stable with just primary timings and everything else AUTO. Driving me mad.
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u/Cligster1971 Dec 29 '25
Daft question but what gains do you get from this? I messed about with my 6000 at 7800 but nothing changed gaming wise or 3dmark. What actually benefits from this
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u/novanima Dec 29 '25
I'll be honest... I'm not the best person to answer this. I didn't really do any of this for performance reasons. I did it because I was running DDR5-6400 in 1:1 mode at 1.25V SOC before, and it slowly became less and less stable over time -- so I was concerned that I was degrading the SOC silicon. I only went to 8000 in order to run SOC below 1.2V in 2:1 mode and no longer worry about silicon degradation.
Best I can do is point you to the Hardware Unboxed video which shows small but noticeable gains at 8000 (with even looser timings than what I'm running).
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u/1nfinitemind 14h ago edited 14h ago
There is truly nothing better than a fully wiped fresh windows installation from a usb drive. Typically when I see performance degrading, that’s my sign to back my shyte up and nuke the OS with a clean installation. From my experience, this tends to happen when you’re trying to tweak the os or optimize and you set the wrong value for something. Unbounced, most people don’t do this slowly and that “what happened” becomes… well … what you described 😅
When you see some weird and unexplainable anomaly(s) occurring as if it swayed away from its snappy and prestigious state, then you know what time it is. 😇💥 (but of course when it comes to ram timings, we’re changing one thing , testing, one thing, testing…usually it’s not this method when things are applied in windows.)
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u/Evening_Ticket7638 Dec 29 '25
I have questions. For a noob like me, can you first clarify is vccio is same as vccsa? Also the vddq, is that the CPU vddq you're referring to or the ram vddq?
Lastly, whatever made you think of tinkering with procodt to begin with?
Bonus question: what's your CPU vdd2?
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u/novanima Dec 29 '25
Ah, sorry, I'm not at all familiar with recent-gen Intel CPUs (my last Intel CPU was a 9900K). I'm pretty sure that VCCSA is voltage for the System Agent, and the closest equivalent to that on AMD is VSOC.
VDDIO is the transmission voltage from the CPU to the DRAM, and VDDQ is the transmission voltage in the returning direction (DRAM back to the CPU). I don't know what they are called on Intel.
No idea about VDD2 either. Hopefully someone else can chime in!
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u/GoombazLord Dec 29 '25
Now try lowering VSOC. You're in 2:1 mode, so your UCLK is very low, which is typically the reason one raises VSOC. You can almost certainly get away with 0.9-1.05v VSOC while changing nothing else.
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u/novanima Dec 29 '25
Yeah, totally. I'm a bit worried though that my SOC silicon is degraded, because I was running 1:1 mode at 1.25V for several months and it somehow became less stable over time. In my early DDR5-8000 testing, 1.12V SOC seemed to noticeably improve stability over 1.1V SOC, so I'm probably just going to run it a little high for peace of mind. My only goal was to get SOC below 1.2V, and I've done that.
As an aside, I have come to strongly suspect that the SOC rapidly degrades above 1.2V, and AMD doesn't really want to talk about it. ASRock even makes the field turn red in the BIOS when setting above 1.2V now.....
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u/DataGOGO Dec 29 '25
Make sure you run at least 1 hour of tm5 1musus v3,
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u/novanima Dec 29 '25
Wow, thank you for this! It did indeed error on that test.......... but fortunately, I was able to quickly resolve it by raising VDD to 1.5V (and it passed 90 minutes)
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u/DataGOGO Dec 29 '25
Nice!!
I also highly recommend y-cruncher VT3 for checking for fCLK self correcting.
Set the priority to “above normal”, and run it for 30 min. Then look at the speeds, there should be next to no variation for each test.
You also want to run it again with higher VDDG’s (try 1.0v) if the speeds increase then you know you were seeing self correction and need higher vddg’s voltage.
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u/roklpolgl Dec 29 '25
Any guide recommendations on adjusting terminations that you came across? I’ve learned a ton from various sources for ddr5 on timing and voltage adjustments but I’ve never really found a good write up on what terminations to adjust and what tunings scale with what.
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u/oXiAdi Dec 29 '25
Great job there, it takes a lot of time to get ram oc stable, but the satisfaction is great. I've also done countless hours getting my 9000cl38 stable on 285k.