: CPU Core Speed decreases from 4.7 Ghz to 293 MHz under GPU stress test
: CPU Core Speed decreases from 4.7 Ghz to 293 MHz under GPU stress test
I'm attempting to optimize my CPU with an older configuration.
CPU model: Intel Core i7-4790k
Memory specifications: Asus Maximus VII HERO
RAM: G Skill Trident X DDR3 2400MHz CL10 2x16 GB
GPU: Gigabyte GeForce GTX980Ti 6144MB 384bit Gaming G1
CPU cooler: Noctua NH-D15S
Power supply: Super Flower Leadex Platinum 750W
OC settings:
- CPU Core Ratio Limit: 47 (per core)
- Minimum Cache Ratio / Maximum Cache Ratio: 40 (uncertain if correct)
- CPU core voltage range: 1.250 / 1.260 (both function in stress tests)
- CPU cache voltage: auto (generally works)
Memory settings: XMP Profile #1 at 2400MHz – default values
I tested OC speeds from 4.0 to 4.7 GHz. All runs were stable during stress tests.
However, during GPU stress tests, my CPU core speed decreased from around 4.7 GHz to 293 MHz every few seconds. Everything was normal during CPU and memory tests.
This issue only occurred during GPU stress when the maximum OC reached 4.5 GHz, with CPU cache voltage set manually to 1.150. In other tests, even with 1.250 or 1.260, it remained stable.
For higher GPU speeds, the problem persisted. I used auto CPU cache voltage and higher core voltages without improvement. The temperatures stayed within normal limits, usually below 80℃.
What might be causing this?
- Screen visibility during CPU stress test / before GPU stress
- Visible drop during GPU stress test
Bios settings:
1. Edit1#: CPU stress test in HeavyLoad app works for over an hour.
2. Edit2: Running at 4.5 GHz was stable, but Blue Screen appeared after 5-10 minutes in Prime95.
I returned to default BIOS and only changed XMP profile #1, but the issue persisted.
During GPU stress tests, I observed frequent drops to 293 MHz in every few seconds. The temperatures remained acceptable.
I have experienced spikes to 300 MHz under default BIOS, and core voltages even at default settings fluctuated widely (1.262v to 1296v).
Hello there! Could you let me know the BIOS version you're using for your motherboard?
@Exige
CPU-Z isn't showing the Bus Speed correctly. It's not possible for Intel CPUs to operate at 6 MHz.
Intel CPUs rely on shared monitoring timers. It's possible that certain software is disrupting CPU-Z's ability to monitor your CPU.
Consider using HWINFO or Intel XTU instead.