Temperature rising by 40 degrees in under ten seconds!
Temperature rising by 40 degrees in under ten seconds!
Alright, so I have an i5 4670K
with the stock cooler and running at the stock 3.4GHz
and an ASROCK Z97 Fatal1ty motherboard. I was getting abysmal FPS in Planetside 2 (we're talking 10-15 FPS here!) and the in-game FPS monitor said that my CPU was the limiting factor (which is bs but that's another story...).
I've had this setup for 2 years now so I figured I might as well try to overclock it and see if it really would make a difference in PS2 or not. I downloaded 64bit CoreTemp, RealTemp, CPU-Z, hwinfo and prime95. I upped the overall clock speed per core to 4.0GHz (where Win 10 would boot and run without getting the WHEA unrecoverable error), started up CoreTemp and RealTemp. All the cores were idling at about 50C. I started up prime95 with 4 worker threads and set the torture test to use small FFTs and
both CoreTemp and RealTemp said that the core temps jumped 30C in less than 5 seconds. After 2 minutes it was saying that the core temps were fluctuating between 95 and 100C, basically at the max allowed temp for the CPU.
I thought this was strange, so I changed the clock speed
back to the stock 3.4GHz and tried the same test again (idle temps then 100% core utilization temps) and there was basically no difference other than maybe 5C max. I turned the PC off, and felt the stock cooler and it was barely even warm.
I spoke to a friend and he recommended reseating the CPU and reapplying thermal paste so I did that. The arctic silver I had on there was basically completely gone so I figured that a new layer of that would surely do something.
I started up the PC, made sure the clock speed was the stock 3.4GHz, tried the idle and 100% FFT temp test again and no difference.
How is it possible for the temps to jump up that quickly? That doesn't seem possible to me. Are my sensors broken? What would you recommend?
Two points to keep in mind. Avoid running two temperature monitoring programs at once, such as core temp and real temp simultaneously. Stick to using only realtemp. This configuration is tailored for Intel CPUs and works well with prime95 usage.
Secondly, it seems you're likely using prime95 version 28.x, which isn't optimal for Haswell CPUs. You should opt for version 26.6—the most recent one that reliably executes standard instructions. Newer versions of p95 demand very high AVX instruction sets, which are particularly demanding on Haswell architecture and not suitable for other applications. This can cause the CPU to operate far beyond its intended temperature limits, similar to pushing it to 130% when it's not feasible.
Two points to note. Avoid running two monitoring programs simultaneously, such as core temp and real temp, especially for Intel CPUs and Prime95. This approach works best with real temperature readings. It was designed specifically for Intel CPUs and Prime95 version 28.x. For Haswell processors, version 26.6 is the most suitable, as it supported normal instruction performance. More recent versions of P95 rely heavily on AVX instructions, which are demanding for Haswell architecture and not practical for other applications. This can cause the CPU to exceed safe operating temperatures. It’s similar to pushing the CPU beyond its designed limits.
So, stick with Realtemp and use p95v26.6 with a small FFT before retrying your tests.
Yes, Intel CPUs are ideal since their core sensors are positioned close to the processor, and software reading them detects rapid temperature changes under load.
Before proceeding further, consider resetting the BIOS to factory defaults (usually F5). It’s easy to overlook settings during optimization, which can disrupt performance. It may also be wise to research your current BIOS configuration thoroughly before attempting more changes, as stability and compatibility are crucial for this process.
If you believe you've understood correctly, you're trying to push the stock heatsink beyond its intended limits. The standard heatsink is adequate for regular stock clocks and wasn't designed for overclocking. For serious overclocking, consider using an aftermarket cooler. If you're on a tighter budget, the Hyper 212 EVO is a solid, affordable option that can handle moderate overclocks. Just ensure your case has enough space for a 159mm model; otherwise, you might not fit it properly.
As Karadjgne mentioned, the latest Prime 95 versions include AVX instructions. Intel CPUs supporting AVX will increase voltage when handling AVX tasks by up to 0.1V, leading to significant temperature rises. The last version without AVX support is 26.6. You may need to search for this information directly since I haven't found a reference on the Prime 95 site.
Thank you for your feedback. I noticed Prime95 26.6 is displaying significantly lower temperatures, which makes sense now—I’ll need to invest in an aftermarket cooler if I want to continue this project. I came across an overclocking guide at the provided link that outlines expected overclocks for various models and recommended starting voltages, so I’m confident I’ll be ready once my new heatsink and fan arrive. Appreciate you bringing up the older version of Prime95 and confirming that a rapid temperature rise is both possible and anticipated.
No worries. It's a good day when ya learn something new, that's useful