9900k at stock throttling under prime95

[poonsies]

Hi all,

Im running my 9900k at stock with my Asus z390-I set to XMP1 enabled and MCE disabled. All cores run at 4700mhz at idle. When I run Prime95 (latest and 26.6) it starts with all cores at 4700mhz but after 30-40 seconds the cores drop to 4300 even though the temps are only around 63 degrees. When the core frequencies drop the temps drop to 40ish degrees. Anyone know why this obvious throttling is happening ?

System:

9900k stock
Kraken x62 AIO
Asus ROG Z390-I
16gb G.Skill Trident 3200 DDR4
1TB Samsun 970 Nvme SSD
2080ti with g12 aio bracket/ Corsair H55
Corsair SF750 PSU
NZXT H200 case

[PC-LAD]

System:

9900k stock
Kraken x62 AIO
Asus ROG Z390-I

If i were to say, I think it could possibly be from the VRM throttling. You are using an aio so there is no active cooling over the MOSFETs. Being such a powerful processor, the cpu has thermal headroom so when it boosts it draws more power putting more demand on the vrm. It heats up, and then the cpu throttles to compensate

[scaryjim]

Just a thought - the base speed of the CPU is only 3.6GHz, so a 4.3GHz all-core boost under an artificially high load isn't what I'd call "obvious throttling". It's still hammering along at ~20% over stock speeds. Those stock speeds aren't listed for fun, you know

So while it could be VRMs overheating, it could simply be the CPU hitting its power limit. No amount of cooling can stop the CPU drawing power, and it will have current and voltage limits as well as temperature limits.