Intel Core i7-4790K review

When Intel launched its ‘Haswell’ range of desktop processors in 2013 many component-watchers were a little underwhelmed. The desktop processors had better, more powerful integrated graphics processors, but there wasn’t much of an increase in outright processing power, and the built-in GPUs still weren’t as powerful as those in AMD’s chips. The original Haswell processors were also criticised by enthusiasts who were disappointed by their limited overclocking potential.

2014’s Core i7-4790K, codenamed ‘Devil’s Canyon’, seems to be a response to these complaints. The new chip has both faster base and boost clock speeds than its predecessor, the Intel Core i7-4770K, with a base clock speed of 4GHz and a Turbo Boost of 4.4GHz, compared to 3.5GHz and 3.9GHz. The i7-4790K can operate at these higher clock speeds thanks to extra capacitors that help deliver power to the die and a new thermal interface material to improve cooling. Otherwise, there is little difference between the chips.

The Core i7-4790K is based on a 22nm process and has four CPU cores, as well as an integrated Intel HD Graphics 4600 graphics processor. The chip has an 88W thermal design power (TDP), which is slightly higher than the Core i7-4770K’s 84W TDP. This means the i7-4790K will run slightly hotter and consume slightly more energy than its predecessor, so will be in need of the extra cooling provided for by its design.

Like the Core i7-4770K, the Core i7-4790K benefits from Intel’s Hyper-Threading technology, which means that processor’s four physical cores are split into eight logical cores, theoretically improving multitasking performance and performance in multi-threaded applications. It also has the same 8MB of Level 3 cache as the i7-4770K, which is shared equally between all the processor’s cores.

As with other Haswell processors, the Core i7-4790K is compatible with Socket LGA1150 motherboards. It’s designed for motherboards that use the Intel Z97 chipset, and will also work happily in older Z87-based motherboards, although you may need to update the board’s firmware to enable it.

PERFORMANCE

We tested the Core i7-4790K in an Asus Z97-Pro motherboard with a SilverStone Argon AR03 air cooler. At its stock speeds, it scored 124 overall in our multimedia benchmarks, which perform a number of intensive desktop tasks such as image processing, video encoding and playing back HD video while performing other intensive tasks. This is a 14-point increase on the Core i7-4770K’s result of 110 overall in the same motherboard. The processor’s improved heat dissipation seems to be effective, as all four cores ran at a solid 4GHz in the multitasking section of our benchmarks.

We’d read reports of overclockers getting the i7-4790K up to 5GHz, so we were understandably keen to overclock the chip. With our AR03 air cooler, we managed to get the processor running at 4.7GHz stably on all cores, at which speed our test system produced a great score of 133 overall. Annoyingly, we couldn’t clock the processor any higher without our test system becoming unstable. We may have got seen better results with a liquid cooler, but even on air we were hoping to see 4.8GHz from this chip.

The Core i7-4770K and i7-4790K both use the same graphics processor, the Intel HD Graphics 4600, so the Core i7-4790K doesn’t provide any advantage over the Core i7-4770K in graphics performance. The Core i7-4790K failed our 1,920×1,080 Dirt Showdown benchmark and produced an average frame rate of 31.2fps in Dirt Showdown at a resolution of 1,280×720, with graphics detail set to High and 4x anti-aliasing. You may be able to play some older 3D games if you’re willing to compromise on graphics quality and resolution, but the Intel HD Graphics 4600 GPU is better suited to watching videos, browsing the web and running productivity applications than serious gaming.

The Core i7-4790K is a powerful, overclockable processor, and we think it’s the processor the Core i7-4770K should have been. The Core i7-4790K provides a fair increase in processing performance for just a few pounds more than the Core i7-4770K, and is well worth the extra cash.