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Tested: Intel's Haswell CPU On The Desktop

By Loyd Case

The details of Intel's newest CPU are finally out, and we've tested the chip for desktop PCs. Anyone considering an upgrade should know that the primary improvements to Haswell over previous Core CPUs lie in two areas: power consumption and graphics performance. But there are many other considerations as well.

The massively deep reviews on Haswell, Intel’s fourth generaton Core CPU, have now hit the web. Making sense of all the data is more difficult, though. So let’s begin with a chart, rather than burying it later in the article.

Whoa, look at that idle power number!

This is the system power usage for three different systems. The key takeaway is the idle power number: 24 watts less than Ivy Bridge at the same clock speed. Most desktop PCs run at idle or near idle far more than they run under load. For example, when you’re typing in Microsoft Word, your system is really idling for the most part. So keep that idle power number in mind as we try to answer question of whether desktop PC users should upgrade to Haswell.

The Modern Desktop CPU

Haswell is considered a new architecture by Intel – a “tock” in their tick-tock product development model. If you look at just the CPU cores, the overall enhancements are evolutionary. Branch prediction has been beefed up a bit, the cache has been improved. Most of the changes to the actual core are minor; even Intel admits that.

Note the phrase “No change in key pipelines.” The CPU cores themselves have only been tweaked in minor ways.

The main changes to Haswell have been in two areas: power and graphics.

The most important change on the power side is moving the voltage regulators onto the CPU itself, which Intel dubs “FIVR” – fully integrated voltage regulator. It’s just another step in the road to moving increasing functionality to the CPU itself. Building the voltage regulator onto the CPU reduces platform power, and also enables Intel to more closely couple the built in System Agent to the voltage regulator. Additionally, Intel has tweaked overall power management inside the CPU and GPU, enabling much faster switching between PC power states.

All that taken together enables the exceptional idle power performance. And this is just the desktop CPU, Intel’s Core i7 4770K, which lacks the deepest S0ix “active idle” state that will be part of the mobile versions of Haswell.

On the graphics side, the main Intel building blocks have been beefed up.

Intel’s GPU architects tweaked much of the GPU pipeline, including substantial improvements to the texture sampler and adding DirectX 11.1 capability. However much of the performance increase is because Intel beefed up the core GPU compute capability, by adding four additional execution units to the core building block of the GPU, which Intel calls the “slice.” The higher-end GT3 graphics cores add a complete second slice, doubling the number of execution units. Higher clocked versions of GT3 are given a whole new name: Iris Pro. Here’s how it all breaks down:

Intel now has three different models for its GPU line.

The Iris Pro 5200 adds a 128MB embedded DRAM (eDRAM) cache which consists of separate dies built into the CPU package to improve throughput. You won’t be able to buy a socketed GT3 CPU at the present time. Intel feels that anyone buying a higher-end desktop CPU will likely be also using a discrete graphics card. However, GT3 models will be available in some all-in-one desktop PCs, where the added performance will be welcome.

The bottom line: the best of Intel’s new graphics cores will be in laptops and mobile platforms, with the exception of some AIO PCs. For most serious desktop PC users, that won’t matter.

A New Socket

Yes, Intel is releasing yet another socket, but their hand was forced when they integrated the voltage regulator. The new LGA 1150 socket is still roughly the same size as the past LGA 1156 and LGA 1155 CPU sockets, so existing CPU coolers will work with the new socket. But new motherboards will be required for Haswell.

Intel seems to have gotten it right with the new DZ875KLT-75K motherboard… except for that mouthful of a name.

I’ve been running the spiffy new Intel DZ87KLT-75K. It’s the first motherboard from Intel that makes me really regret Intel exiting the motherboard business in a couple of years. Combining a nice mix of I/O layout, lots of fan headers, Thunderbolt port and one of the most logical UEFI BIOSes I’ve seen, it’s a sweet, performance-oriented board. Curiously, it only offers a single video output connector, an HDMI 1.4a port, but Intel probably figured a high-end board would more likely use a discrete graphics card anyway.

The new motherboards include new core logic, with the flagship Z87 offering the richest set of features.

The Z87 is mostly about I/O; almost everything else in in the CPU now.

Asus, Gigabyte, MSI and others are introducing an array of Z87 motherboards. In addition, motherboards using the H87 and B85 chipsets will also support Haswell, albeit with more limited feature sets.

Performance Testing

Here’s the set of platforms I used for this round of testing.

ComponentHaswell SystemIvy Bridge SystemSandy Bridge System
CPUCore i7-4770KCore i7-3770KCore i7-2600K
MotherboardIntel DZ87KLT-75KAsus P8Z77-V PremiumAsus P8Z77-V Premium
MemoryCorsair DDR3-1600Corsair DDR3-1600Corsair DDR3-1600
Primary StorageCorsair Force GT 240 SSDCorsair Force GT 240 SSDCorsair Force GT 240 SSD
Power SupplyCorsair TX-850wCorsair TX-850wCorsair TX-850w
GPUNvidia GTX 780Nvidia GTX 780Nvidia GTX 780

These are high-end systems all around, which is appropriate for a high-end Core i7. Will a high-end GPU make the CPU completely irrelevant? It’s a question worth asking when you’re considering upgrading.

Will a high-end GPU make the CPU performance gains and power savings completely irrelevant?

I also threw in FutureMark’s new PCMark 8 into the mix. PCMark 8 has the usual set of tests based on built-in Windows applications. However, FutureMark added some cool new features. The most important, from my perspective, are actual application tests. If you have Microsoft Office and the Creative Suitesubset of Adobe content creation applications, you can run applications-based benchmarks.

The Microsoft Office test uses just three Office apps: Word, Excel and PowerPoint. The Adobe test uses Photoshop, After Effects, InDesign and Illustrator. Notably absent is Premiere Pro.

The standard “Creative” benchmark (which doesn’t require Adobe apps) includes a number of video and audio encoding tests, as well as performance from four-way video conferencing, so I threw that into the mix. The PCMark 8 “Home” test suite includes some photo editing and casual gaming.

I also dug deeper into the new 3DMark (confusingly just called “3DMark” now), taking a look at the CPU impact on physics calculations. Finally, I also took a look at three high-end PC game titles, Bioshock Infinite, Tomb Raider and Metro Last Light.

Let’s examine how it all turned out.

Performance: PCMark 8

Finally having a benchmark suite that incorporates professional graphics applications is something I’ve wanted for a long time, even if video editing isn’t part of the mix.

Steady performance improvements as we move up the generations.

The Adobe tests suggest a 20% improvement in overall performance moving from Sandy Bridge to Haswell. The Micrsoft Office tests also showed substantial gains over CPU generations. On the other hand, the standard PCMark 8 benchmarks show more modest gains: 10% from Sandy Bridge to Haswell in the Creative test, for example.

The bottom line is that if you’re mostly running light duty applications, you’ll see little performance benefit moving to Haswell, even from Sandy Bridge. If you’re a power user, however, upgrading starts to look pretty interesting if you’re still on Sandy Bridge. The jump from Ivy Bridge to Haswell is less compelling.

Then again, the improvement in idle power is substantial, so there’s that to consider as well.

3DMark and Gaming

First let’s consider the base 3DMark test.

It all looks the same…

There’s a whopping 2.5% increase in the 3DMark score moving from the Core i7-2600K to the Core i7-4770K – not exactly a lot to write home about.

Here’s what happens when we break out the scores for the individual tests.

No difference in graphics; big difference in physics.

The difference in physics scores is over 22%. That’s a big number.

Different games will result in different performance improvements, depending on game design, engine design and related factors. Given a high-end graphics card, it’s natural to run games at very high levels of eye candy. Let’s look at three games in quick succession, all run at “Ultra” detail levels.

The impact of the CPU also depends on whether the game is GPU bound or not. If the CPU isn’t having to wait for the CPU, its performance matters more.

The Bioshock Infinte and Tomb Raider built-in benchmarks are almost “pure” graphics tests. Yet while we see zero improvement in Tomb Raider based on the CPU, Bioshock Infinite’s benchmark goes up 17% over the Sandy Bridge system at 1080p resolution. At 1440p, the GPU is obviously being hammered more, so the CPU spends more time waiting – so the impact of CPU performance is lower.

Different games are, well, different. It’s been my experience that the Unreal Engine, used in Bioshock Infinite, is more sensitive to CPU performance than other graphics-intensive games. On the other hand the Metro Last Light test, which looks more like real gameplay, sees extremely modest gains going from one CPU to the next. An RTS or turn-based strategy game heavy on AI will likely see more substantial boosts based on CPU. The impact of the CPU also depends on whether the game is GPU bound or not. If the CPU isn’t having to wait for the CPU, its performance matters more.

Should You Upgrade?

The last piece of the puzzle is pricing. Here’s a rundown of Haswell desktop CPU models and pricing. I’ve taking the liberty of condensing Intel’s array of model numbers a bit, leaving out the Core-i7 4770R, which you can’t buy and couldn’t use if you did get one, since it’s not a socketed CPU.

CPUi5-4670Ti5-4670Si5-4670i5-4670Ki7-4770Ti7-4770Si7-4770i7-4770Ki7-4765T
Price$213$213$213$242$303$303$303$339$303
Base Freq.2.3GHz3.1GHz3.4GHz3.4GHz2.4GHz3.1GHz3.4GHz3.5GHz2.0GHz
Turbo Freq.3.3GHz3.8GHz3.8GHz3.8GHz3.7GHz3.9GHz3.9GHz3.9GHz3.0GHz
Cores/Threads4/44/44/44/44/84/84/84/84/8
TDP45W65W84W84W45W65W84W84W35W
L3 Cache6MB6MB6MB6MB8MB8MB8MB8MB8MB

Note: the price is Intel’s price per 1,000 units; retail parts will cost more. As an example, the Core-i7 4770K is currently selling for $350 online. Also, the “K” products are unlocked for simple overclocking, if that’s your thing, but the i7-4770K offers a higher base clock than the i7-4770. As in the past, the key difference between the Core i5 and Core i7 CPUs is hyper-threading (the Core i7’s have it) and a somewhat larger L3 cache on the Core i7s.

But CPU price isn’t the only factor in parsing this upgrade decision: the new CPUs require a new socket, LGA 1150. So you’ll need to consider the roughly $100 - $400 motherboard upgrade cost, depending on which of the new motherboards fit your bill. Notes: the price is Intel’s price per 1,000 units; retail parts will cost more. As an example, the Core-i7 4770K is currently selling for $350 online.

The one cadre of users left out in the cold are those who have invested in extreme high-end Sandy Bridge Extreme (LGA 2011) systems. Those still offer huge memory bandwidth compared even to Haswell, but there’s no hint of an upgrade path for SBe users.

If you’re running a Sandy Bridge system, upgrading to Haswell bears serious consideration, particularly if you’re a power user running lots of heavily threaded applications. You’ll see significant performance gains and overall lower power consumption, unless your system runs under heavy load all the time – a fairly unlikely scenario.

The move from Ivy Bridge to Haswell is less clear. You may see performance gains of up to ten percent, but in most cases, it will be less. Power usage is lower, of course, but that’s really not enough to drive the cost of a motherboard and processor swap. If you’re running an older, Nehalem or Bloomfield CPU CPU, it’s definitely worth the upgrade. You will see some pretty healthy performance gains, as well as lower power consumption.

That’s Haswell on the desktop, in a nutshell. We’ll take a look at mobile Haswell in the future. The gains for mobile users look to be more substantial than desktop users, which is certainly key to Intel’s future, since laptop and ultraportable PC sales are the one bright spot in the PC growth arena.