Maximum safe voltages for a 4790K?

I would say 1.2V for ensured extra long life. Even 1.25 could be considered, but I won't go more.

Some people posted 4.5 Ghz 4770Ks with 1.2. Some people posted 4.3 GHz with 1.3. It is luck of the draw, but I do believe 1.2 should get you in the 4.4-4.5 GHz area considering it is a 4790K, but it is all luck in the end. Make sure you have a high-end cooling. Haswell heats like an old USSR oven. I don't think your 212X is going to be enough for 4.5 GHz on all cores with good temps. Aim to for lower than 70C temperature.

You can get liquid cooling if you definitely want to squeeze the maximum.

A high end air cooler like Cryorig R1 Ultimate, Phanteks PH-TC14 or Noctua NH-D14 and NH-D15. But know that these are 1 kg and up coolers, so if you have a motherboard with a thin PCB like a 2/4 layered - the cheap MSI Z97 or ASRock Extreme3 and you tighten too much - you might warp your motherboard.


P.S Also add Thermalright Silver Arrow, Archon and True Spirit 140 Power and be quiet! Dark Rock Pro 3 in the CPU cooler list.

Getting 4 cores @ 1.256v @ 4.6Ghz.
1 core @ 4.8Ghz @ 1.231v

Pretty darn stable..... I had a few BSOD but upped a little the voltage to what it is at and it's 24/7 BOINC running, also ran RealBench for 24hours straight on stress test and no issues now. I think I am real lucky! Also, it's running on air cooler. Cpu cores are 72deg. I am looking into getting water cooled.

depends on the quality of your motherboard and power supply and your cooling system. if all three at top of the mark, most would agree that 1.40v@65c is as high as you want to run 24/7/365.

I'm also looking for an answer.
I'm running my i7 4790k stable at 4.8ghz 1.280v max temp 66C (51C avg) tested for 30 minutes on CPU-Z stress.

Do you think this is safe?

I still trying to lower the voltage, I'll keep you posted.

wait, if people pushing 1.45V on 6700K which is 14nm, how than 1.3V is considered possible not safe for Haswell/Devil ?

i get a automatic reboot when i try to run x48 ratio at 1.270v do i need to do anything else? disable XMP or something what about ram speeds? I am at 4.7 at 1.247v stable on h80iv2

Guys,

Different Microarchitectures such as 65, 45, 32, 22 and 14 nanometers have different maximum recommended Core voltages, so don't confuse Haswell / Devil's Canyon Vcore with Sky Lake / Kaby Lake Vcore.

Also, here's the recommended operating range for Core temperature:

80°C Hot (100% Load)
75°C Warm
70°C Warm (Heavy Load)
60°C Norm
50°C Norm (Medium Load)
40°C Norm
30°C Cool (Idle)
25°C Cool

Keep in mind that load and idle Core temperatures are influenced by Ambient temperature. Normal or Standard is 22°C or 72°F.

Overclocking is always limited by two factors; voltage and temperature. No two processors are identical; each processor is unique in voltage tolerance, thermal behavior and overclocking potential, which is often referred to as the "silicon lottery" or luck of the draw.

We know that excessive heat over time damages electronics, so even when using manual Vcore settings, excessive Vcore and Core temperature may result in accelerated "Electromigration" - https://www.google.com/?gws_rd=ssl#q=Electromigration

This prematurely erodes the traces and junctions within the processor's layers and nano-circuits, which will eventually result in blue-screen crashes that become increasingly frequent over time. CPU's are more susceptible to Electromigration with each Die-shrink, however, Intel's advances in FinFET technology have improved the voltage tolerance of their 14 nanometer Microarchitecture.

Here’s a list of maximum recommended Vcore settings:

-> Core i

7th Generation 14 nanometer ... 1.400 Vcore
6th Generation 14 nanometer ... 1.400 Vcore <---
5th Generation 14 nanometer ... 1.400 Vcore
4th Generation 22 nanometer ... 1.300 Vcore <---
3rd Generation 22 nanometer ... 1.300 Vcore
2nd Generation 32 nanometer ... 1.350 Vcore
Previous (1st) Generation 45 nanometer ... 1.400 Vcore

-> Core 2

Legacy 45 nanometer ... 1.400 Vcore
Legacy 65 nanometer ... 1.500 Vcore

When tweaking your processor near it's highest overclock, keep in mind that for an increase of 100 MHz, a corresponding increase of about 50 millivolts (0.050) is needed to maintain stability. If 75 to 100 millivolts or more is needed for the next stable 100 MHz increase, it means your processor is overclocked beyond it's capability.

With high TDP air or liquid cooling you might reach the Vcore limit before 80°C. With low-end cooling you’ll reach 80°C before the Vcore limit. Regardless, whichever limit you reach first is where you should stop and declare victory.

Remember to keep overclocking in perspective. For example, the difference between 4.5 GHz and 4.6 Ghz is less than 2.3%, which has no noticeable impact on overall system performance. It simply isn’t worth pushing your processor beyond recommended Core voltage and Core temperature limits just to squeeze out another 100 MHz.

You might want to give this a read: Intel Temperature Guide - http://www.tomshardware.com/forum/id-1800828/intel-temperature-guide.html

CT