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What Intel's Haswell Means for Desktop CPU Choices

By Loyd Case

Loyd breaks down the state of integrate graphics and explains what Intel's new CPU means for desktop PC builders, discrete graphics in gaming systems, and all-in-one PCs. In short, desktop CPU choices get more confusing.

Late last week, Intel unveiled some features and performance data for the graphics cores in their upcoming Haswell CPU. Most of the hoopla revolved around Haswell’s graphics performance on laptops, but Intel also disclosed some interesting bits about desktop processors. Before diving into that, it’s worth considering how integrated graphics typically plays out on desktop PCs.

First Puzzle Piece: Performance CPUs Rarely Use IGPs

On the mobile side, most Intel-based laptops currently include their highest end HD 4000 GPU. Laptops are increasingly becoming closed systems, making user upgrades more difficult–and graphics upgrades impossible. So Intel has been fairly smart, integrating its best GPU into all Core class processors. Even Ultrabooks, with their tightly constrained chassis and limited airflow, utilize CPUs with Intel HD 4000 graphics.

People who build PCs tend to be pretty smart about how they’re going to use a system. Building a small, shared living room PC for web access and light office chores? Integrated graphics may be fine, but so is a lower end CPU. Someone who picks up a higher end CPU – a Core i7 3770K, for example – is unlikely to use the integrated GPU. Usually, that system will end up with at least a mid-range graphics card, like a GeForce GTX 660 or AMD Radeon HD 7870.

Intel knows this, and doesn’t really want to spend the die space on putting a higher end integrated GPU into a performance-oriented CPU where the integrated graphics will mostly go unused. A better integrated GPU requires more die space, which increases the overall cost of the processor. That makes sense when you realize that even a relatively low end graphics card, like Nvidia’s GTX 650 or AMD’s HD 7790 substantially outperforms the HD 4000.

Second Puzzle Piece: Shifting Markets

Even if we ignore the steady shift away from desktop PCs towards laptops and tablets, the desktop market itself is changing. Mainstream desktop systems are gradually moving away from deskside tower PCs to all-in-one systems. AIOs have traditionally suffered from anemic graphics performance, even though they’re embraced some cool technologies like advanced sensors and touch.

All-in-ones have constrained thermal environments, which means dropping a big desktop GPU into the chassis is problematic. (Yes, Maingear ships an “all-in-one” with a desktop GPU, but that requires three power bricks and is massive rather than svelte. It’s the very definition of an outlier.) Some AIOs include discrete mobile GPUs, like Nvidia’s GT 650, but graphics performance is still limited.

Now we have two pieces of the puzzle: high end systems tend to have discrete GPUs. More mainstream AIOs have constrained thermal environments. This brings us to this slide, from Intel’s IRIS graphics product announcement:

Note that the Core i7-4770R has the best integrated GPU performance of the high end Intel desktop CPUs.

Why does the Core i7-4770R have a lower TDP (thermal design power) – 65W – than the Core I7-4770K, yet have better graphics? And what the heck does the “R” suffix mean?

The “R” is a new suffix, and refers to versions of the CPU using a BGA (ball grid array) package. This means that the CPU is permanently soldered to the motherboard, not dropped into a socket. From Intel’s perspective, this lowers cost, as BGA packages can be more compact. BGA works more effectively in compact systems, enabling very thin form factors.

Anyone who wants to build a higher-end home theater PC or “Steam Box” with Haswell is out of luck.

The Core i7-4770R CPU includes Intel's top-of-the-line Iris Pro 5200 graphics core (with 128MB of EDRAM) to boost graphics performance in higher-end all-in-one PCs. This will enable PC OEMs to build AIOs offering more desktop-like performance in very thin form factors.

On the other hand, Intel likely doesn’t want to waste chip and package real estate to build GT3 plus EDRAM (Iris Pro 5200) into a socketed desktop part, which will usually have a more performance oriented graphics card.

Of course, anyone who wants to build a higher-end home theater PC or “Steam Box” is out of luck. While the GT2 graphics core that will exist in Intel socketed desktop CPUs offers better performance than current HD 4000 IGPs, it looks to still a modest performer when it comes to PC gaming.

Putting Together The Puzzle: Discrete is Not Dead

What this all really means is that discrete GPUs will continue to thrive on desktop systems for the time being. Even that lowly GTX 650 will outperform a GT2 class Intel IGP. So while Nvidia and AMD may lose some sales volume in laptops and AIO PCs, you’ll still want that graphics card in your desktop PC, even if it’s an HTPC or HDTV-connected gaming rig.

What about the CPU side? Is Haswell better than Ivy Bridge on the desktop? We won’t really know until the official reviews hit the street, which won’t happen until early June. At first blush, Haswell seems to have higher TDPs than Ivy Bridge, which implies that its less power efficient. Those numbers are likely to be deceptive however.

Idle power will almost certainly be lower in Haswell than Ivy Bridge

At last fall’s Intel Developer Forum, Intel talked up some of the power efficiency technologies included with Haswell. While the Core i7-4770K is listed as having a higher TDP than the current Core i7-3770K, the average power use over time is probably going to be lower. And if you don’t use the IGP, then you’ll see even better efficiency.

But we won’t know for certain until we get Haswell CPUs in our hands. But if you think you need a new desktop system today, you probably won’t need to wait for the new CPU if you’re building a gaming rig. But if you’re sitting on the fence at all, it’s probably worth waiting a few more weeks.