Intel Z87 and Haswell 24/7 OC Guide

Intel Z87 and Haswell 24/7 OC Guide

Cooling Considerations »

What's New

Intel's latest platform makes a big change by using the new LGA 1150 socket. The socket uses less pins than previous sockets, but although there are less pins connecting the chip to the motherboard itself, the removal of pins isn't limiting functionality. Rather, the pins were removed because of a simplified power-delivery mechanism to the socket and because the main power regulation devices are now part of the chip itself. Board voltage regulation is still quite important, but rather than power quality being an issue with most value-oriented products, Intel's latest design has made it so that less expensive boards are just as capable as high-end enthusiast products when it comes time to clock your CPU. Those cheaper boards will still require more active cooling over the board VRM section, and perusing videos on YouTube by various reviewers and companies will re-iterate just that, with ASUS very plainly stating that their cheaper boards are exactly as described here: just as capable with better cooling.

That's not the only change the voltage regulation permutation brought about. Since voltage regulation for the chip's individual domains is on the chip itself, cooling required for Haswell-based CPUs has increased to a point where inexpensive but for their highly overclocked cooling performance favored coolers of past platforms aren't up to the same task with Haswell CPUs. The overall heat concentration of highly clocked Haswell chips is different due to the inclusion of the FIVR leading to very different thermal characteristics, which makes some of those $30 coolers that did great with Ivy Bridge completely useless to overclockers of Haswell platforms. Also, since the voltage sent into the chip is doled out to various parts right inside the chip, the controls offered are more complex than ever before, as are the chips and how you overclock them. The Core i7-4770K features far more flexibility than the older Core i7-3770K, with many more options in the BIOS helping you get the most out of your brand-new Haswell CPU.

One of the biggest changes comes in the form of available BCLK dividers. Intel's Haswell allows the BCLK of the chip itself to run at higher frequencies, although the same limits are still imposed by devices connected to the PCIe bus. The introduction of 125 MHz and 166 MHz BCLK dividers allows for much greater flexibility with memory and CPU overclocking, but PCIe devices are still part of the system, so only the same rough deviation of 15% from the base divider, either up or down, is possible. Buying a board with a PCIe slot connected to the Z87 PCH will give you greater flexibility because the base clock of the PCH always sits at the reference 100 MHz, eliminating problems with clock tolerances for PCIe devices connected to the Z87 PCH. Though most slots connected to the PCH only offer a PCIe x4 link, performance isn't affected enough to matter in memory overclocking, but it can have some impact in 3D testing. You can check out W1zzard's PCIe scaling tests using Ivy Bridge to get an idea of how PCIe scaling works HERE.

Haswell CPUs also introduce more memory multipliers (up to 2933 MHz) and more CPU multipliers (up to 80x). Another change is that the CPU's L3 cache speed is no longer derived from the CPU's speed, now featuring it's own multipliers which can auto-adjust to the workload. The iGPU portion of the chip has added flexibility too, but I don't have a lot to share on that specifically since most of us don't use it. The iGPU is much larger and has more horsepower than on past Ivy Bridge CPUs, so it can be a large source of heat, but I will address that in a moment.

In total, we've got a bigger iGPU, added dividers everywhere, and the power regulation. As evidenced by the larger TDP of the Haswell chips, all make for more heat, which has cooling change as well.
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