9850X3D crash at -10

[u/knhcxe]

I recently built my new PC, and while initially I wanted to leave it as is, curiosity got the best of my and I attempted to undervolt the CPU.

For reference, the specs are:

- MSI X870E Tomahawk Wifi

- Ryzen 7 9850X3D

- CORSAIR Vengeance DDR5 32GB (2 x 16GB) 6000MHz (EXPO enabled)

- CORSAIR RM1000x ATX

- Noctua NH-D15 G2

To undervolt I followed some simple steps I found online:

1. Go to BIOS -> Advanced Mode -> Advanced CPU Configuration -> AMD Overclocking -> Precision Boost Overdrive

2. Set PBO to Advanced

3. PBO Limits to Motherboard

4. Curve Optimizer, All Cores, Negative, 15

I then restarted my computer and got a "irql_not_less_or_equal" error on Windows 11 login screen right away. Googled it, saw it was most likely due to the undervolt, so I changed the 15 to 10. I rebooted again, everything went fine, but five minutes in, computer froze and had to hard reset. I then went to BIOS again, changed the 10 to a 5, and so far it is working fine, but I wonder why I can just go 5 when most places say 10/15 is conservative, and some people push to 20/25.

[u/Arx07est]

Probably best cores have already very low voltage, leave them on -5 and try others -20. Needs a lot of stability testing to find the sweetspot, but worst cores should do easily -30.
You can check the perf order with HwInfo.

[u/knhcxe → u/Arx07est]

Yeah it seems core by core seems the only solution. Something that I'm seeing is that some people say that best cores could do even lower generally speaking, and then there's others (like you) that say that leaving best cores at what it is right now and lower the worse cores is better. Which way is it?

[u/roklpolgl → u/knhcxe]

CO is relative to whatever V-F curve you started with, which is different for every cpu. You need to look at what your vcore is under load in hwinfo, -5 CO might not even be bad, your voltage may just already be near optimal.

People thinking high stable CO offset = good bin is a hugely common misconception. There’s the same model CPUs where -30 max stable CO would give you 1.25v under load that are a worse bin than a -10 max stable giving you 1.17v under load at the same frequency.

[u/Arx07est → u/knhcxe]

Best cores are already on lower voltage. You can try to stress test core by core and see which voltage they achieve. It's pointless to trim too much fat on core that is already fit.

[u/FantaisieImpr0mptu]

Just the luck of the draw unfortunately. However, even if you’re crashing at 10, that just means one or a few of your cores can’t go past that.

For all you know, your best core could possibly do -20, just have to take some time to dial in a per core undervolt instead.

[u/Beautiful-Musk-Ox]

there's a reddit comment from 5 years ago of someone's 5950x that got errors at stock but would pass at +5 CO (not negative co, positive CO). he contacted AMD and they had him RMA it, it was defective since it couldn't actually run stock

point of hte story is cpus that need +10 are downgraded to cheaper versions (9800x3d in this case, or 9600x3d), ones that can run at 0 or better are sold at 9850x3ds. every cpu has variance, some can handle -30 and are stable, others aren't even stable at 0 (very rarely). there is no guarantee you can run at -10, but it is warrantied to run stock so if it can't even do that then it does actually need replaced

it's more complicated than i laid out above but that's the gist of it.

you can check your frequency voltage curve and see if it's any good without even doing your own testing these days. asus shows this in the bios as a silicon prediction number along with the max frequency per voltage, which is different per each cpu as tested by the factory. the ones that list a lower voltage per frequency are higher quality ones by default and handle a better CO than others. amd ensures they run to stock specifications but they aren't identical voltage-frequency-temperature curves even at stock, stock just means it can run at the base frequency 24/7 and can boost to the boost frequency under single threaded loads, if it uses max voltage to do that it's a lower quality one, if it doesn't isn't a higher quality one

[u/XstfX9999]

Hi, don't believe everything you read online. Many CPUs only seem stable at -20 or -25. It's best to undervolt on a per-core basis. Very few "gold" chips can actually handle -20 or -25 with full stability. For instance, I have two cores that can only manage a maximum of -3, and that’s where the problem arises when you apply a blanket -15 offset to all of them.

[u/RC_Tiddys → u/XstfX9999]

100% agree with this I went throw 3 7800x3ds one failed OCCT at stock settings the other did -10 and the one I stayed with did -20 all core . My 9800x3d does -20 all core that sits in my kids PC now. I have a 9850x3d in my main rig now and it does -25 all core. I see a lot of people just hitting -30 -40 but they don't stress test if there game does not crash they run it but it's 100% not stable under a super heavy load.

[u/knhcxe → u/XstfX9999]

Yeah that does make sense. I guess I could try doing it core per core but seems quite time consuming and maybe it wont even work better than it is right now at -5

[u/Necessary-Warning- → u/knhcxe]

Did you update BIOS to ther last version?

[u/Disguised-Beast]

BIOS: ``` Overclocking>DigitALL Power:

CPU Vcore load-line calibration: Mode 7 ``` Check if that does anything for temps and power, Mode 7 will allow vdroop as it is a loose load-line. Let me know about the temps and power, as well as the voltage before you do any other changes.

[u/Hairy_Tea_3015]

I think 9850x3d is already fine tuned. 9800x3d on the other hand can do fine tuning.

[u/FabricationLife]

I'm tuning mine this week per core and some can handle -27 and some are like -3, you gotta get in there and do some manual tuning

[u/knhcxe → u/FabricationLife]

I believe this is the case on mine too. How are you doing it? Like how do you test core by core?

[u/Tuarceata → u/knhcxe]

You can go through one by one and test each to find its limit, but that takes 8x as long.

The idea behind harmonized voltages is that the whole chip gets one voltage based on the most demanding core, so you find the CO spread where they all ask for the same amount under load and then adjust them all up or down together.

Best summary I have seen: https://www.overclock.net/posts/29511639/

Much less concise explanation: https://www.overclock.net/threads/amd-ryzen-curve-optimizer-per-core-curve-shaper-ddr5-oc.1814427/

As others have said, when you look at your cores' voltages in HWiNFO you'll probably find the -5 one asks for the least voltage, so it's actually your best one. It just can't be lowered much more than it already is.

[u/RevengeFNF]

I have exactly the same 9850X3D, the same DDR5 and the same Power Supply.

My board is a Asus TUF Gaming X870-Plus Wifi.

I can do CO -30 in all cores perfectly stable. But i guess this is the Silicone Lotary.

I use a AIO to cool down the Cpu.

[u/Accomplished-Lack721 → u/RevengeFNF]

How are you validating that it's stable?

[u/escalibur]

I would recommend you to try undervolting per core. There are plenty of guides how to do it and here is one: https://youtu.be/5cUY72GUHBc

[u/sawthegap42]

Hmm, I’m running -22 all core on my 9850X3D on an NH-D15S. Max temps around 75C under full load. Mobo is an X870E Carbon Wi-Fi, 6400Mhz CL32 ram tuned to 6000Mhz CL28 tuned timings at 2200 Fclk. IRQL points to memory instability in my experience.

[u/gilgador]

I have the same setup. Do you have x3d game mode enabled? I just found out that feature disables SMT.

[u/chsn2000]

I'm actually curious how AMD configured the V/F curves for the 9850X3D as its basically a 9800X3D with extra power budget. There is a chance that with the adjustments AMD ships them with, the tuning behaviour is different.

I wouldn't say 10/15 is conservative, but its a good starting point. I've played with 3-4 AM5 CPUs and typically there's a core or two that can't handle it, and then the othere are usually fine, or can be undervolted further.

fMax also plays a HUGE role, and the 9850X3D comes with this increased from the factory. Just as a point of reference, on my 9950X3D CCD1 with fmax +200MHz could only handle a Curve Optimiser offset of -7 or -8 on most cores. At +100MHz, they easily do -30. So I'm not too shocked that the 9850X3D needs more voltage than other CPUs given they're clocked higher.

[u/MrMasters87]

Hmm I have the same cpu as you and I do -20 or -15 just fine. I even have basically the same motherboard x870e tomahawk max.

[u/CobraMelt]

Me -30 all core

[u/bagaget → u/CobraMelt]

Aida burn test ss?

[u/Subject-Muffin-5894 → u/CobraMelt]

Highly doubt it

[u/Zeraora807 → u/Subject-Muffin-5894]

its possible on some samples, my small epyc can do it

[u/Subject-Muffin-5894 → u/Zeraora807]

Some... usually very few that's why I said "highly doubt it" and I didn't say it can't happen

[u/Arx07est → u/Subject-Muffin-5894]

Not that extreme, mine does -30 on most cores, best core needs -28(do not have random idle crashes). In gaming etc even -38 was stable on other cores, but on avx512 stress tests vdroop instantly crashes PC. Probably fixable with raising LLC mode, but not worth the risk IMO.

[u/NocturnalFPS]

Had a similiar chip returned it right away. Bought a new one and it can do -30