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13900KS +Z690 performance variability problems investigation and solution

1549 Views 13 Replies 9 Participants Last post by  Slackaveli
TLDR: Was having big problems with 13900KS performance and smoothness due to PCIE ASPM being enabled in BIOS.

I have noticed that my brand new 13900KS, that is set to 5.6Ghz / 4.9 @ -100mV offset and was having very variable performance in some low threaded tests.
MicrobenchmarkGui latency was all over the place for same size, Aida was crazy, MLC was not loving me.

Also, package power at idle, with all C-States enabled was like 20W. I have started my investigation from this power -> after some digging, i have noticed that monitoring programs like MSI AfterBurner and HWInfo have quite high CPU load, then in ThrottleStop i have found that one of my cores is never really entering low power states.

It made little sense, so i have worked in BIOS, resettting, reaplying my OC with no results.
The power breakthrough came when I tested "Power saver" power plan. Package Power went down to to 7W at idle and benchmarks were much improved.
It made little sense, in MicrobenchmarkGui (large pages) i was getting perfect latency stair with power saver, but as soon as i enabled High Performance plan, it was bad again.

After resetting power plans in WIndows, some more toying, i realized -> HWInfo and Afterburner must be very busy with something, and in HP plan they are polling CPU non stop, while PowerSaver is probably tuning them down.

With this "discovery" i was finally on track to solving it: HWInfo64 has column - "Profiling Time" that can be enabled in settings and it was showing crazy times, like 500+ for my 3090:
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I knew something was very wrong and suspected ASPM being enabled -> after trip to BIOS and disabling it, everything went back to normal, benchmarks have rock stable scores, package power when idle is <3W and cores are properly sleeping now as it should be:

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So if anyone is having strange trouble, it might be worth visiting BIOS and checking ASPM settings, on idle system Hwinfo profiling should be real fast for anything not connected via USB.
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thank you for this,I am looking too upgrade mij 12700k too an 13900ks,but wanted too make sure it works.I have the same mobo as you.So how is the performance overall with this cpu on this motherboard(the msi edge z690 ddr4)
 

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Interesting.. I dont have such issue, but when I was testing this I noticed that when I enable Power saver plan, my 13700k draws around 18W at idle.. when I enabled balanced again it went down to 4W.. lol.
 

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Discussion Starter · #4 · (Edited)
thank you for this,I am looking too upgrade mij 12700k too an 13900ks,but wanted too make sure it works.I have the same mobo as you.So how is the performance overall with this cpu on this motherboard(the msi edge z690 ddr4)
I upgraded from 12900K that was doing 3800C15 to 13900KS that does 4100C16 on same DR 4000C16 ram kit ( had it for a day now, saw it boot 4300 gear 1 ).
My experience is not applicable as i ran it stock for short time - perf was fine, power usage huge as expected, 40k cb23 stuff.

Then i treated it like my 12900K - disabled ****** cores, disabled HT, and went for sweet spot in undervolt and static clocks. Settled on 5.6 and -100mv undervolt and 4.9 uncore ( 1.25V effective ).
Total 15% upgrade from previuos 12900 @ 5ghz @ 135mV undervolt ( 1.2V effective ). My peasant 280mm cooling is right on spot for this.

MB is fine as always, VRMs barely braking a sweat, just that minor gotcha with ASPM in E7D31IMS.1A1 beta bios.

EDIT: what more can a casual OC man ask from his system than this:

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You Go Joe! :)
 

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Just checked my MSI board, ASPM was disabled by default. Very strange. FYI you can also set ASPM behaviour in windows power plan. The high performance plans have it disabled while the balanced plan is set to moderate power savings.

e: Even though it was disabled in BIOS after I disabled it in windows power plan I have much less frametime spikes in RTSS?
 

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With the plethora of information provided it is simple to blame it on the motherboards (auto) pick of secondary and tertiary ram timings and call it a day with the proposal to retrain the ram a few times (with fast boot disabled).
There are also a lot of strong opinions out there stateing that changeing a cpu should always go hand in hand with a fresh windows install.
Software wise you can do a simple sanity check with latencymon. If the bar stays green in idle you can start telling the bios who is boss.
Lastly there was an issue with the latest intel chipset drivers. One versions addon for the 13900ks has been screwed up. I do not know if your motherboard is affected though.

Good luck!
 

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There are also a lot of strong opinions out there stateing that changeing a cpu should always go hand in hand with a fresh windows install.
This I don't get.. yes everyone can have opinions but from SW perspective there is nothing to gain there, unless people tinkered with their OS beyond normal user interaction and they then basically restore it to normal condition.
 

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Hey, can you explain exactly what you mean with "5.6Ghz / 4.9 @ -100mV". Is that a VF point where you set the offsett? Do all other VF points and MHz above 4.9GHz then operate using that offset?
Thanks
 

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My 13700kf could hit 40ns but the 13900ks is hitting a wall around 50ns(DDR4). I was on the v19 bio and I also tried the new v1A bios.
13700k has lower latency than 13900k due to less ecores = shorter ring = lower RTL.
 
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