[SOLVED] 8700k downclocking more than AVX offset set to?

[thewalleprod]

OCed my 8700k @ 4.6ghz on all cores with 1.27v and LLC of Level 3. I set the AVX offset to 2 in BIOS but when running Prime95, I notice that the clocks go down to 4200mhz instead of 4400mhz if the offset is 2. Power limits are set to max, Core VIDs are requesting anywhere from 1.3-1.42v. When I disable AVX in Prime95 testing, the AVX offset is normal and will fluctuate between 4600mhz and 4400mhz. With AVX enabled, it's dropping down and staying at 4200mhz. Am I doing something wrong in the OC?

 

[~cw]

If you're doing a sync all cores multiplier I don't think the frequency should fluctuate in non-AVX Prime95 workloads. If the CPU's throttling back even before you get the AVX offset, it could still be due to VRM temperatures. Are you running HWInfo and watching the package thermals and power limits? Are you using 1.27v because it was unstable at lower voltages? x46 all-core may be possible on stock vcore. Try LLC on 4 or 5. When you worked up your overclock were you using AVX tests or non-AVX only? What's your cooling like? What's your motherboard?

 

[thewalleprod]

If you're doing a sync all cores multiplier I don't think the frequency should fluctuate in non-AVX Prime95 workloads. If the CPU's throttling back even before you get the AVX offset, it could still be due to VRM temperatures. Are you running HWInfo and watching the package thermals and power limits? Are you using 1.27v because it was unstable at lower voltages? x46 all-core may be possible on stock vcore. Try LLC on 4 or 5. When you worked up your overclock were you using AVX tests or non-AVX only? What's your cooling like? What's your motherboard?

mobo is an Asus Prime Z370-A. Yes I got a BSOD. I used both on Prime95. With AVX enabled and disabled as well. Cooling is good. Max CPU package temp is 75-79C under stress testing after 10-15 minutes. In Hwinfo64 there is no limits under my CPU like throttling or thermal throttling.. CPU cache ratio is set to 42. Maybe that’s why it’s underclockijg down to 4200mhz?

 

[~cw]

Cache (uncore) between 300 to 500 MHz lower than clock is OK. In a perfect world you run both core and cache ratios identically at the cost of greater power draw. Are you using adaptive/offset voltage control or manual? Have you altered any other voltages? (VCCIO, VCCSA etc)

If you try just jumping straight to 1.29 V vcore with a 'middling' LLC of 4 does it still aggressively underclock? Would be interesting to know if hwinfo in sensors mode shows any thermal throttling during testing.

What motherboard and cooling setup do you have?

 

[thewalleprod]

Cache (uncore) between 300 to 500 MHz lower than clock is OK. In a perfect world you run both core and cache ratios identically at the cost of greater power draw. Are you using adaptive/offset voltage control or manual? Have you altered any other voltages? (VCCIO, VCCSA etc)

If you try just jumping straight to 1.29 V vcore with a 'middling' LLC of 4 does it still aggressively underclock? Would be interesting to know if hwinfo in sensors mode shows any thermal throttling during testing.

What motherboard and cooling setup do you have?

I'll go up to 1.29v with LLC of 4 and see results. I only have manual voltage set, I didn't alter anything else in terms of voltage.

Motherboard is an Asus Prime Z370-A, I have 3 intake fans on bottom 120mm each, 4 exhaust fans 120mm each and a H100i AIO 240mm for the CPU.

 

[thewalleprod]

Cache (uncore) between 300 to 500 MHz lower than clock is OK. In a perfect world you run both core and cache ratios identically at the cost of greater power draw. Are you using adaptive/offset voltage control or manual? Have you altered any other voltages? (VCCIO, VCCSA etc)

If you try just jumping straight to 1.29 V vcore with a 'middling' LLC of 4 does it still aggressively underclock? Would be interesting to know if hwinfo in sensors mode shows any thermal throttling during testing.

What motherboard and cooling setup do you have?

With AVX disabled in Prime95, it stays steady at 4.6ghz.. With AVX enabled, it underclocks still to 4100mhz.

 

[~cw]

With AVX disabled in Prime95, it stays steady at 4.6ghz.. With AVX enabled, it underclocks still to 4100mhz.

What are your temps when this occurs? Have you run OCCT with some AVX workloads to log the per-core and TjMax values while benchmarking? It still might be power or secondary thermals given that excessive drop.

I would be tempted to remove any AVX offset then adjust your motherboard's TjMax to handle AVX workloads. It's just one school of thought but might be worth consider if your motherboard supports it, because so many apps nowadays include AVX optimised instructions. Doing this would at least eliminate any AVX offset frequency drops.

On Asus boards (I have a Maximus XI Hero) you can set Maximum CPU Core Temperature which effectively adjusts the TjMax. Other boards are similar.

https://www.overclock.net/threads/the-utter-uselessness-of-the-avx-offset-in-gaming.1777315/ may be food for thought.
Buildzoid did a video in 2020 considering whether to AVX offset or not.

View: https://www.youtube.com/watch?v=fmBDFYyFAcQ


Mentioned in that Overclock.net article, ThrottleStop (which I've used for a few years on my older laptop to undervolt its core and cache) can also let you set profiles with different AVX offsets if you need it.

 

[mdd1963]

Most 8700K owners were shooting for at least 4.7 GHz on all cores, as that was the single core max turbo anyway.

I'd consider defaulting your BIOS to defaults, setting XMP, enabling MCE (which should strive for 4.7 GHz all core if thermals and power budget /VRM temps allow), then perhaps installing /configuring Intel's XTU for the AVX offsets, +/- core voltage tweaks, actual desired all-core clock speeds, etc... (in the event of a crash, or any unclean shutdown, XTU will default back to stock settings, which eliminates getting into any real trouble with BIOS settings.)

 

[Karadjgne]

You set VID (voltage supplied by the VRM's) to 1.27v. Prime is asking for 1.3v+ for a 4.4GHz all core. The cpu will further downclock to stay under VID supply by cpu demand. To get 4.4GHz in Prime, you'd need to bump the VID over what the demand is by a +offset voltage of 0.2v.

 

[Karadjgne]

AVX for the most part (I've seen) is a moot point in gaming. Most static OC's disregard the AVX offsets entirely as it messes with the clock speeds and voltages, which isn't a preference when tuning vcore to within 0.0x volts of instability.

Most games don't use AVX to any real degree, very few (if any) use AVX-2 and none use AVX-512. What little AVX is used is only for things like vector analysis in explosions and particle trajectories etc, so the slight increase in temps is very temporary and not really a concern.

Even bios ignores AVX when an offset is engaged, up until the cpu discovers it's using AVX at all, then kicks in the offset, which can upset fps in an otherwise smooth game. Most cpu temps are far enough under Tjmax that even a 5° bump for a few seconds isn't worth mentioning and doesn't really affect performance.

So it's usefulness is limited to those few ppl gaming without overly sufficient cooling and the cpu is already on the edge of throttling.