Question 9900K unstable during AVX Prime95 stress tests.

Mar 18, 2020
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Hi guys, I'm running a 9900K @ 5Ghz. Got very unlucky with the lottery, and I need 1.34 V for stable OC, and temps hit 93c on Cores 2 and 4 (with h100i AIO)

After running various stress tests with no problem, including pre AVX Prime95, I gave Prime95 v 28 (AVX) a go, as my last rig could manage it even when OC'ed.

After 20 seconds, it blue-screened, so I set the offset to -2, and tried again. This time it lasted beyond 20 seconds, but when the temps his 97c I stopped the test...

Given that I can't seem to get a stable 5ghz for AVX, but everything else is so far so good, should I call it quits and consider it stable for real life applications, or should I be able to run AVX loads on it (even though I wouldn't in real world applications), and consider an RMA

Thanks for any advice!
 
Mar 5, 2020
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If it's not working properly, that's a no no, and given that you can't seem to get a stable 5Ghz, i would call it quits and RMA it.
 
Feb 24, 2020
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Hi guys, I'm running a 9900K @ 5Ghz. Got very unlucky with the lottery, and I need 1.34 V for stable OC, and temps hit 93c on Cores 2 and 4 (with h100i AIO)

After running various stress tests with no problem, including pre AVX Prime95, I gave Prime95 v 28 (AVX) a go, as my last rig could manage it even when OC'ed.

After 20 seconds, it blue-screened, so I set the offset to -2, and tried again. This time it lasted beyond 20 seconds, but when the temps his 97c I stopped the test...

Given that I can't seem to get a stable 5ghz for AVX, but everything else is so far so good, should I call it quits and consider it stable for real life applications, or should I be able to run AVX loads on it (even though I wouldn't in real world applications), and consider an RMA

Thanks for any advice!
you could upgrade your watercooling with a larger radiator i've seen quit a few opinions on the net now that 240mm isn't big enough for a 9900k.
im kind of in the same place as you with a 9700k i started looking at how many watts my cpu was drawing while stress testing and how much it was drawing while gaming. i ended up putting mine back to 4.9ghz the extra hundred megahertz just doesn't make much difference performance wise
 
Mar 18, 2020
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you could upgrade your watercooling with a larger radiator i've seen quit a few opinions on the net now that 240mm isn't big enough for a 9900k.
im kind of in the same place as you with a 9700k i started looking at how many watts my cpu was drawing while stress testing and how much it was drawing while gaming. i ended up putting mine back to 4.9ghz the extra hundred megahertz just doesn't make much difference performance wise
Its super annoying because if I got luckier with the lottery, I would've been able to get to 5Ghz at 1.32 v instead of 1.34. So the extra power on top of the 1.34 that's required for AVX instructions simply sucks too much power at 5Ghz, and creates too much heat, even with a -2 offset.

I'm considering re-seating the block using Arctic MX 4 thermal paste. If I can get my temps down by 5 or 10 c, I may just get away with a fully AVX stable, albiet with a -2 offset, at 5Ghz with manageable temps. I can't see my chip achieving full AVX stability without an offset, there's just no way i'd be able to cool the chip at the Vcore it would require.

I'm gonna contact Intel and ask their opinion, hopeful they'll be able to shed more light on the matter.

For more background, I'm using 1 click XMP, I've got my ring ratio set to 4.7 Ghz as recommended in the MSI z390 OC guide, and I've set my LLC to level 4 to keep the Vdroop curve flat, for as little variance as possible.
 

Phaaze88

Splendid
Ambassador
floored63 is correct. A 240mm AIO is on par with high end air coolers and they aren't enough to OC a 9900K either - for stock operation, either is obviously fine.

I strongly recommend a 360mm AIO or custom loop for 9900K overclocking. 280mm is ok, but when you're trying to push this cpu as far as you can go, 280mm isn't enough either - still in a better spot than 240mm and air cooling.


By the way, here's Silicon Lottery's binning statistics for successful 5.0ghz 9900K OCs: https://siliconlottery.com/pages/statistics
Normal Freq.AVX 2 Freq.Vcore% Capable
9900K4.80GHz4.60GHz1.275V100%
9900K4.90GHz4.70GHz1.287VTop 91%
9900K5.00GHz4.80GHz1.300VTop 30%
9900K5.10GHz4.90GHz1.312VTop 5%
 
Reactions: Ezio_-_Auditore
Feb 24, 2020
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floored63 is correct. A 240mm AIO is on par with high end air coolers and they aren't enough to OC a 9900K either - for stock operation, either is obviously fine.

I strongly recommend a 360mm AIO or custom loop for 9900K overclocking. 280mm is ok, but when you're trying to push this cpu as far as you can go, 280mm isn't enough either - still in a better spot than 240mm and air cooling.


By the way, here's Silicon Lottery's binning statistics for successful 5.0ghz 9900K OCs: https://siliconlottery.com/pages/statistics
Normal Freq.AVX 2 Freq.Vcore% Capable
9900K4.80GHz4.60GHz1.275V100%
9900K4.90GHz4.70GHz1.287VTop 91%
9900K5.00GHz4.80GHz1.300VTop 30%
9900K5.10GHz4.90GHz1.312VTop 5%
thanks for the link great info
 
Reactions: Ezio_-_Auditore

alceryes

Distinguished
You won't be able to RMA it.
The 5GHz boost frequency is NOT a guarantee and, even if it was, is only for ONE core. the ability of the i9-9900k is heavily tied to the cooling solution you are using. Get a better cooling solution and you'll be able to clock higher.
 
Reactions: Notorious^

Notorious^

Prominent
Feb 17, 2019
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Alceryes is spot on

As a fellow 9900K owner let me just say that 240 AIO IS NOT enough to cool that 9900k on benchtesting. I'm sure it will cool just fine in gaming and surfing the interwebs. Cooling that CPU is everything! Colder it is, higher it will boost. I was on a 280 AIO and i could get stable 5.0 & 5.1 GHz OC on most benchtests except for AVX. Stepped up to a 360 AIO and its better by far and i can achieve 5.2GHz on all benchtests with temps in the mid 80c's - still hot yes, but i can complete the tests without a BSOD where as on my 280 AIO it would run for a minute or two and BSOD.

My gaming temps are in the mid to high 40c's when gaming and idles at a cool 27c. Only time it gets hot is when i overclock the piss out of it for benchtests. I can hit 5.1GHz all cores using 1.23V and monitoring via HWiNFO64

Another element to this is what motherboard do you have? Higher end motherboards have better VRM's and better stability for OC'ing. Also what is your settings for your overclock? I'm not concerned about AVX personally, there is nothing i do or run for long periods of time to stress my CPU like running prime etc.

I would upgrade your cooler if anything. If you can run other benchmarks like 3D Mark, Cinebench R15, R20 and stress it for 30 mins with no BSOD's i would say your fine. What do you use your PC for? Do you have your cooler setup on a fan curve? Pump on extreme when benchtesting?
 
Last edited:
Mar 18, 2020
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Alceryes is spot on

As a fellow 9900K owner let me just say that 240 AIO IS NOT enough to cool that 9900k on benchtesting. I'm sure it will cool just fine in gaming and surfing the interwebs. Cooling that CPU is everything! Colder it is, higher it will boost. I was on a 280 AIO and i could get stable 5.0 & 5.1 GHz OC on most benchtests except for AVX. Stepped up to a 360 AIO and its better by far and i can achieve 5.2GHz on all benchtests with temps in the mid 80c's - still hot yes, but i can complete the tests without a BSOD where as on my 280 AIO it would run for a minute or two and BSOD.

My gaming temps are in the mid to high 40c's when gaming and idles at a cool 27c. Only time it gets hot is when i overclock the piss out of it for benchtests. I can hit 5.1GHz all cores using 1.23V and monitoring via HWiNFO64

Another element to this is what motherboard do you have? Higher end motherboards have better VRM's and better stability for OC'ing. Also what is your settings for your overclock? I'm not concerned about AVX personally, there is nothing i do or run for long periods of time to stress my CPU like running prime etc.

I would upgrade your cooler if anything. If you can run other benchmarks like 3D Mark, Cinebench R15, R20 and stress it for 30 mins with no BSOD's i would say your fine. What do you use your PC for? Do you have your cooler setup on a fan curve? Pump on extreme when benchtesting?
Thx for reply!

I think I've just got a bad chip. I need 1.34 to hit 5.0GHZ with LLC on level 4 and uncore set to 4.7 for true stability. Lower voltage than that and I'll bsod if, say, I run Prime 95 non AVX and then open a game concurrently. The extra demand is enough to crash the rig. 1.34 is what I need for full stability (not inc AVX). I'm running XMP. Mainboard is MSI MPG Z390 gaming pro carbon AC

With AVX, I bsod after 20 seconds, and my temps hit 100c. With a -2 offset, I can go past 20 seconds, but temps will hit still hit 100c after a couple of mins even though Vcore goes right down for some reason when running AVX loads.

Regarding fan curve, I use Icue with pump and fans set to extreme, and they reach max speed at 80c.

You mention that your cooling enables you to reach 5.2 at low voltage. I was under the impression that bclk limitations are set by the voltage required for each chip, hence the silicon lottery. You imply that your cooling has given you stability at lower voltages? I've always understood that good cooling simply allows you to run at HIGHER voltages because your cooling can handle the additional heat produced. I've never heard of good cooling reducing the power required by a given chip to hit certain speeds, meaning that better cooling might enable me to go up to 1.35, run AVX with no offset, and not fry my chip, but I can't see it giving me stability at Vcore anywhere near what you've got.

I use my rig for gaming, and haven't yet seen my chip go past 65c during gaming. Average is prob 50c, so I guess i'm nitpicking abit, I'm unlikely to ever need AVX, or even to stress my rig anywhere near Prime95 levels. I suppose I'm just trying to workout if there's anything I can do, or if I've just lost bad at the lottery.
 

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