Does using a small FFT version of Prime 95 that supports AVX help figure out if the 9900k overclocking is stable?
Does using a small FFT version of Prime 95 that supports AVX help figure out if the 9900k overclocking is stable?
LLC should be left at auto unless it's not enough for the OC. If that's the case, you'll need something like 3 out of 5 or turbo but no extreme settings. Without it, the 9900k might fail to boot or crash Windows because the CPU hits a voltage too low to keep going. Almost funny watching him get frustrated with this.
Oh wow, that was so annoying. He handled things way better than I would have. Honestly, I don't get how this connects to me right now. His system wouldn't start when he switched back to EVGA settings because he skipped the usual boot process and just went for overclocking. It didn't mention LLC at all, but it did say V was too low to start. I'm fine in my setup and can run almost anything except P95 with AVX. Every guide I've read says to set LLC around 5 or 6 out of 8 on Asus boards. But if you go way too high, things could get unstable or even cause invisible voltage spikes that might hurt your CPU. So maybe I'll try again tomorrow.
The point I was trying to make is that at stock settings, J2c LLC was set to auto, so the actual voltages weren't enough to actually boot with that CPU, but they would pass post-check. By overclocking the CPU and manually setting LLC, he bypassed that and gave him just enough to stay stable. Your PC does something similar: vdroop isn't supplying enough when LLC is set to auto, so the OC fails at 4.9GHz. Asus is correct. A 5/6 out of 8 is medium to medium high, which is perfect for almost all overclocking attempts; 7/8 is honestly for pros and world record hackers. LLC is an extra voltage boost. The CPU loads change constantly, going from highs to lows. It's when the voltage drops low that vdroop happens. When the CPU suddenly needs power, before the VRM can bump up the voltage, the CPU runs out of juice, causing a BSOD. So LLC was added as a pre-emptive voltage to cover those dips for the instant when things get hard. That way, the PC stays stable. Because it's an extra applied voltage, it also affects how much peak power is taken from the VRMs and puts less stress on them. So you only need to set enough voltage to cover that drop in vdroop, not too much to swamp the CPU or put undue strain on the VRMs. So you'd drop the base voltage to maybe 1.2v, add 5 LLC, which bumps the total vcore up to around 1.3v (still set for 1.2v). This would give you a swing of about 0.1v instead of the 0.15-0.20v you see now.
Okay thanks for the help. I get it now. My LLC is already set to 5 and my max swing is 0.155, so maybe I should try LLC6 even though some people have had issues with it? Or maybe I could just increase the vcore to fix the droop. Sorry if that sounded confusing. I'm still figuring out all of this stuff. Full settings: Vcore - 1.30v, 4.9GHz on all cores, 0AVX Offset, Cache Ratio 45, LLC - 5, DRAM - 1.35v, VCCIO - 1.1v, VCCSA - 1.1v
Your numbers are mostly right, but tweaking things can make a huge difference depending on the CPU model.