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[Solved] My 9900k is a lemon

Relevant components:

Case: Lian Li o11 Dynamic, 6 Corsair LL120 case fans
Motherboard: Gigabyte Aorus Ultra Z390 (latest F7 BIOS)
Cooler: h100i V2 (Stock Fans replaced with 2 Noctua NF-F12 and ran at 100%)
Thermalpaste: Thermal Grizzly Kryonaught

Purchased in September last year (so I am guessing I just had a bad spin at the silicon lottery on the early silicon).

My 9900k will not be stable at stock frequencies with a manual vCore of pretty much anything less than 1.4 v, and at that point I hit thermal issues. I can run it at optimized defaults with the big fluctuations in voltages, but that it is the max performance I have managed for rock-solid stability. I cannot pass a Prime95 small FFTs torture test without adding an AVX offset of 2, even at stock and with the relevantly higher-end cooling solution detailed above.

MCE on and I get BSOD before I can even get past the Windows login screen. Intel Performance Maximizer is not compatible with my BIOS.

Does anybody else have anything even remotely like this? I do not believe the majority of OCs posted on forums are legitimately rock-solid stable, but I must have a lemon!

If it’s not stable at stock clocks, why not return to the store?


It is stable at stock voltage (but not if I set it manually), but gets extremely hot.

It is not purchased from a store, it was purchased from a large business distributor. Although it is a retail sample. If I had purchased it from Amazon, it would have gone back a long time ago. It would have to be a lengthy RMA to Intel at this point

Stupid question, but did you remove the plastic on the heatplate of the cooler?

Another thing: disabled all “core enhancement” features in BIOS.

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I had a phenom that, at brand new, had to underclock to function. I never really looked into it as I don’t know anything about this stuff, but I’ll assume you are having the same deal.

ONly thing I’ll say, shoulda bought threadripper.

I would reseat the CPU in the MB and of course re-install the cooler in the process and try again.

I would also suggest to try other benchmarking tools,
like OCCT for example.
And run some Cinebench tests.
Prime95 can be pretty torturing on intel cpu´s really.
Also run some program´s and games, render a video or what not.
And see if the system acts any weird, and monitor temps.

What @MazeFrame said. Also check thermal paste applied properly.

Also… be aware of MCE in the BIOS and also be aware that intel cpus are only specced to maintain their intel spec BASE clock. BOOST is a temporary thing. You may get lucky with a CPU that can maintain boost (and a lot can), but the spec is to only be able to maintain base. The flip-side is that your cpu may be weaker than others.

Well man I’d say return if you can but if you can’t… Next time consider hitting one of the popular silicon lottery sites and order a binned chip and never tell people you did so they just think you got lucky :wink:

i would set avx offset to. atleast 3 or greater. Should not be noticeable in any use. do you ran high ram oc? xmp on or off? bios and firware updates done?

if nothing helps i would deli… wait that was soldered right? Then better not do that.

I actually did leave that on on one build :slight_smile:
Dropped 15 degrees when I went to reapply paste and found it :slight_smile:

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I just had a ryzen system that ran a gigabyte board the damn thing was never stable come to find out it was the board… Try a cheap board off amazon after trying all of the other tricks here. you might be surprised. If it works send beer…


I re-seated the CPU and reapplied paste and it never made a difference. I created an RMA with Intel and they agreed to it, but they never had any in stock so didn’t know how long it would until I get another!

Amazon were selling 9900ks for cheaper than RRP , so I purchased another chip myself to test it out. My new chip is so much better in terms stability at higher frequencies, but I am running it at 4.8GHz with an AVX offset of 1. I still cannot run a Prime95 AVX stress (small FFts) without it jumping straight up into thermal throttling territory. I test CPUs to find the instabilities, I don’t just run Cinebench once and call it stable. I can run Cinebench back-to-back for several minutes and have it sits in the high 80’s C - low 90’s C.

Not impressed with the thermal performance on these CPUs. Would need some top quality silicon and be able to under-volt for it to be as stable as I would like. Looks like I will be putting a 360mm AIO on here, as this 240 is not cutting it! I loved how cool my Ryzen 7 1700 ran, even overclocked

Thanks for the help!

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