Unable to OC beyond 4.8GHz on water with 4790k

[Colonel_Panic]

I work for a company developing a line of custom waterblocks and we're currently testing some examples with a Devil's Canyon 4790K i7 chip.

My job so far has been to boost clock speed so that we can gather CPU temperatures across a variety of blocks but getting any stability above 4.8GHz has so far proved impossible. Auto voltage to 4.8 was pretty easy, but as soon as I boosted the multiplier to 49, even manually boosting voltage to crazy levels didn't produce a stable system with IntelBurnTest (boots to Windows every time).

From what I've read, 4.9 GHz seems to be a very tough level to crack, with most users reporting 4.7 or 4.8 limits. Are the odds of a 5.0+ capable chip that slim or is there something I may be missing? Some reports seem to have 1.5V Vcore required but I didn't hit that yet (stopped at 1.49 to read more). My method is basically lock the bclk and increment the multiplier, with a related voltage increase. I realize super stable overclocks are as much art as science but it'd be nice to get some stability at a high clock.

 

[Colonel_Panic]

I didn't really mess with any of those settings. Looking around online, I see a few people winning the lottery with 5GHz at 1.375V and a few at 5 GHz with 1.55V so I may push the voltage up a little further before declaring an impasse. Temperatures are pretty low with our new block setup so I'll see how it goes.

 

[PliotronX]

You can safely put input voltage up to 2.1v or a little more which can help with mega clocking. Lower the cache ratio to eliminate that variable and its own voltage (a.k.a. ring bus) can be 1.2v or a little more. System agent voltage can help with memory clocks or general stability at 1.1v. I also noticed some odd behavior with my Asrock; it will actually ramp up the clock above the targeted maximum momentarily while under load by changing BCLK on its own (100MHz in BIOS). When I was testing at 4.7GHz, it was randomly jumping to 4.9GHz. There is quite a challenge to OCing this platform to the hairy edge.