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9900k idles at 4700mhz

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Posted · Original PosterOP

Hi all,


I have recently upgrade my pc to a 9900k, Asus z390-I motherboard, 16gb G.Skill Trident 3200 DDR4 and a 2080ti. I enabled XMP1 in the bios to let the RAM run at its native 3200mhz but my 9900k seems to idle at 4700mhz on all cores with an occasional second dip to 800 after this change. When running Cinebench the clock speeds don't seem to change at all which is odd but the temps do spike up to 60ish. Is this normal ?


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that's because you enabled MCE (multicore enhancement). Turn it off you want your C-states back.

Studying abroad, ditched the crappy laptop for a do-all laptop double. Dried factory CPU paste, long memory timings, cooler cools the inductors but not the mosfets and an inch of unused internal space on both left and right

Model: HP Omen 17 17-an110ca CPU: i7-8750H (0.125V core & cache, 50mV system agent undervolt) GPU: GTX 1060 6GB Mobile (1696MHz 0.812V ~ 1860MHz 0.95V) RAM: 12GB DDR4-2666 19-19-19-43 2T Storage: 128GB Toshiba NVMe SSD (KBG30ZMV128G) + 1TB Seagate 7200RPM 2.5" HDD (ST1000LM049-2GH172) Monitor: 1080p 120Hz IPS G-sync


The best thing to do is reading the clock speed that doesnt end in a pair of zeros. Software voltage readings are wrong if your motherboard's not a high end model

CPU: i7-2600K 4493MHz (multiplier: 43x) 1.35V (software) --> 1.4V at the back of the socket Motherboard: Asrock Z77 Extreme4 (BCLK: 104.5MHz) CPU Cooler: Noctua NH-D15 RAM: Adata XPG 2x8GB DDR3 (XMP: 10-11-11-30 2T 2133MHz, custom: 10-11-10-30 1T 2229MHz) GPU: Asus GTX 1070 Dual SSD: Samsung 840 Pro 256GB (main boot drive), Transcend SSD370 128GB PSU: Seasonic X-660 80+ Gold Case: Antec P110 Silent, 5 intakes 1 exhaust Monitor: AOC G2460PF 1080p 144Hz (OC'd 150Hz) TN Keyboard: Logitech G610 Orion (Cherry MX Blue) with SteelSeries Apex M260 keycaps Mouse: BenQ Zowie FK1


Results: Cinebench R15 Single thread:159 Multi-thread: 770 (thx Meltdown Spectre patch) Super Pi (v1.5 from Techpowerup, PI value output) 16K: 0.11s 1M: 8.4s 32M: 7m 45.9s

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welcome to the Linus Tech Tips forums!


more than likely, you'd changed the setting in the UEFI/BIOS to use MCE (Multi-Core Enhancement) option.

its usually an ask when you use the XMP setting in RAM.

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Posted · Original PosterOP

Ah that makes sense. I turned MCE off in the bios and set Windows to the balanced Power Management Profile. The cores now seem to fluctuate very quickly between 800mhz and 4700mhz which I guess is normal ? 


On a side note I tried out the Cinebench single core test just to see if it did indeed hit the magic 5ghz number. From what I can see in CPU-Z all the cores ramp up to 4700mhz and Realtemp implies that different cores are being picked for short bursts of the benchmark. Is this how it normally works ? I assumed it would use just 1 specific core for the whole test?

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The way the turbo boost works on the 9900K is 5GHz on single thread, 4.7GHz on all threads, the temps and performance you're seeing is perfectly normal, and I see you already got the downclock problem resolved with MCE. 


Just got one of these myself about 2 weeks ago, loving it so far. 

Primary Rig (new, just built):

CPU: Intel i9-9900K @ 4.7/5.0GHz (1.25V/1.29V)  ~  Mobo: Gigabyte Z390 AORUS Master

CPU Cooler: Thermaltake Floe RGB 280mm AIO (Push/Pull with Thermaltake Riing & Pure fans)

RAM: 4x8GB G.Skill TridentZ RGB @ 4000MHz CL17-17-17-38 1.4V (F4-3600C16Q-32GTZR) 

GPU: eVGA GTX 1080 Ti FTW3 Hybrid @ Stock/2050MHz - Push/Pull Radiator Fans

PSU: eVGA SuperNova P2 1200W - Case: Thermaltake View 91

SSDs/HDDs: Samsung EVO 860 1TB, Transcend 480GB, Samsung QVO 1TB, Seagate FireCuda 2TB (Hybird HDD)

Windows 10 of course - which I don't mind, so far

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Posted · Original PosterOP

Ok so now I have more odd behaviours. With Prime95 running I get about 20-40 seconds of all cores working on 4700mhz then all of a sudden they all drop to 4300mhz and stay there. During the start of the test temps don't exceed 65 degrees so iy cant be a thermal throttling. Any ideas ?

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