Can't boot even on a tiny overclock on X99P-SLI and i7-8520K set in BIOS

[romandesign]

I tested the CPU overclocking within Windows in "Gigabyte Intel Extreme Tuning Utility" - it easily runs on x36 with default voltage and x40 with 1.15V - just the two settings I tried. However if I'm changing core frequency in BIOS even to x35 without touching anything else - I get the "failed boot" message, suggesting to reset to "optimized defaults" or enter BIOS. Same if I also increase VCore voltage - I tried up to 1.3V. It doesn't make any sense, I know overclocking is working fine with this CPU, at least up to x40 on 1.15V, but I can't set it up in BIOS even with x35. As soon as I set on default x34 - it boots fine.

Everything is on defaults and auto settings, except boot setting set to my SSD. BIOS is updated to version 20 (latest at 1 week ago). I have a very large CPU cooler, and I'm not trying anything extreme. What's happening?

Does anyone know what could be the problem? Thanks.

[risey]

I had a similar problem but OC the memory using XMP1, kept rebooting until I got the bios error. I have OC the CPU but used the APP center, that works fine. I did contact support and was told to try the latest beta bios, F22I, that gave me a major error, windows 10 would start up, load up then bsod, had to go back to F21. So whatever they tell u, stay away from F22I...

[vanhoud]

I tested the CPU overclocking within Windows in "Gigabyte Intel Extreme Tuning Utility" - it easily runs on x36 with default voltage and x40 with 1.15V - just the two settings I tried. However if I'm changing core frequency in BIOS even to x35 without touching anything else - I get the "failed boot" message, suggesting to reset to "optimized defaults" or enter BIOS. Same if I also increase VCore voltage - I tried up to 1.3V. It doesn't make any sense, I know overclocking is working fine with this CPU, at least up to x40 on 1.15V, but I can't set it up in BIOS even with x35. As soon as I set on default x34 - it boots fine.

Everything is on defaults and auto settings, except boot setting set to my SSD. BIOS is updated to version 20 (latest at 1 week ago). I have a very large CPU cooler, and I'm not trying anything extreme. What's happening?

Does anyone know what could be the problem? Thanks.

Did you get it to overclock? Did you switch the CPU mode on the motherboard to "OC"?