The solution was unstable during AVX Prime95 stress tests.
The solution was unstable during AVX Prime95 stress tests.
Hi guys, I'm running a 9900K @ 5Ghz. Had a bad luck with the lottery, need 1.34 V for stable OC, and temperatures reached 93c on Cores 2 and 4 (with h100i AIO). After stress tests—including pre AVX Prime95—I tried Prime95 v 28 (AVX) and it worked, even when OC'ed. After 20 seconds it blue-screened, so I adjusted the offset to -2 and retried. This time it lasted longer than 20 seconds, but when temps hit 97c I stopped the test... Given I can't consistently get stable 5ghz for AVX, but everything else is fine, should I give up and think it's stable for real use, or should I still try AVX loads (even if not ideal) and consider an RMA? Thanks for any advice!
Alceryes is spot on
As someone who owns a 9900K, I can confidently say that a 240 AIO isn’t sufficient to keep that CPU running smoothly during bench testing. It should work just fine in gaming and browsing the web. Cooling the CPU is crucial – the colder it gets, the better performance it delivers. I used a 280 AIO and managed stable speeds of 5.0 and 5.1 GHz on most tests, except for AVX. When I upgraded to a 360 AIO, it performed significantly better; I consistently reached 5.2 GHz across all benchmarks with temperatures in the mid-80s – still hot, but I completed the tests without BSOD, unlike my 280 AIO which would crash after just a minute or two.
My gaming temperatures sit in the mid to high 40°C range during play and idle at around 27°C. The only real issue comes when I push the CPU to its limits for overclocking.
If it isn't functioning correctly, that's unacceptable, and since you're unable to maintain a consistent 5GHz connection, I recommend proceeding with an RMA.
you could improve your watercooling by using a bigger radiator, as more people have suggested online now that a 240mm isn't sufficient for a 9900k. i'm in a similar situation with a 9700k, so i began checking the wattage my cpu was consuming during stress tests and gaming. after reviewing the numbers, i decided to keep it at 4.9ghz since the extra hundred megahertz doesn't significantly affect performance.
It's really frustrating when I didn't get lucky with the lottery, but if I had better odds, I could have achieved 5Ghz at 1.32 v instead of 1.34. The extra power needed for AVX instructions at that frequency is too much and causes excessive heat, even with a -2 offset. I'm thinking about re-seating the block with Arctic MX thermal paste. If I can lower my temperatures by 5 or 10 degrees, I might be able to run a fully AVX stable version at 5Ghz without overheating, though it would still need a -2 offset. I don't think my chip can reach full AVX stability without an offset because cooling the chip to the required Vcore would be difficult.
I plan to reach out to Intel for their insights on the issue. For more context, I'm using 1 click XMP with a ring ratio of 4.7 Ghz as suggested in the MSI z390 OC guide, and I've set my LLC to level 4 to maintain a flat Vdroop curve. This helps minimize temperature variation.
This message will align nicely with the RMA Authorization team.
"The CPU temperatures are elevated when running all cores at 400 MHz above baseline!"
Click! <dial tone!>
floored63 agrees. A 240mm AIO matches premium air coolers and isn't sufficient for overclocking a 9900K. For stock builds, either is acceptable. I suggest a 360mm AIO or a custom loop if you're aiming for high overclocks. 280mm works, but pushing this CPU further requires more space—still better than 240mm with air cooling.
By the way, here are Silicon Lottery's binning stats for successful 5.0GHz 9900K overclocks:
https://siliconlottery.com/pages/statistics
You won't be able to return it for repair. The 5GHz boost frequency isn't a certainty, and even if it were, it's only applicable to one core. The i9-9900k's performance is closely linked to the cooling system you have. Upgrading your cooling solution will help you achieve higher speeds.
Alceryes is perfectly accurate
As someone who owns a 9900K, I can confidently say that a 240 AIO isn’t sufficient to keep the CPU cool during bench testing. It should work just fine in gaming and browsing the web. Keeping the CPU cooler makes a big difference—higher temperatures mean better performance. I used a 280 AIO and was able to maintain stable speeds around 5.0 and 5.1 GHz on most tests, except for AVX. When I upgraded to a 360 AIO, it performed significantly better; I consistently reached 5.2 GHz across all benchmarks with temperatures in the mid-80s—still hot, but I completed the tests without any crashes.
My gaming temperatures sit in the mid to high 40°C range during play and idle at around 27°C. The only time things get really hot is when I push the CPU beyond its limits for bench testing. I can maintain 5.1 GHz across all cores using 1.23V, and I monitor it with HWiNFO64.
Another factor is your motherboard. High-end boards offer better VRM and more stability for overclocking. Also, what are your overclock settings? I’m not too concerned about AVX since I don’t run long sessions stressing the CPU (like Prime).
If you need a cooler upgrade, I’d recommend one. If you’re running other benchmarks such as 3D Mark, Cinebench R15 or R20 and stress-testing for 30 minutes without any BSODs, I’d say you’re in good shape. What’s your PC used for? Do you have a fan curve cooler or pump, especially during bench testing?