AMD and Intel: Corsair Labs : Intel Core i7 Build & Architecture Changes

Corsair Labs : Intel Core i7 Build & Architecture Changes

Vishnu

Introduction - The "Old" Way

Intel's newest architecture, known as Nehalem (nee-HAY-lem), is an interesting and mysterious beast. There are some of the most significant changes in years inside this bad boy, so let's get straight to the point.

The biggest and most important change for us to talk about today is the memory controller. The memory controller, much like its name implies, is the interface between the memory and the processor. Typically located on the "North Bridge" chip on the motherboard, the memory controller communicated to the processor through the "Front Side Bus" or FSB.

THE OLD WAY - A SYSTEM WITH A FRONT-SIDE BUS

In this image, the FSB is the connection between the processor(s) and the memory controller. Notice the memory controller is the interface between the CPU and the memory, as well as the interface between the CPU and the I/O controller, which would control your hard drives, USB ports, etc.

In the past, overclocking was usually achieved by tweaking this FSB. For example, on a Core 2 Duo system where the processor's multiplier is locked, we might have seen the FSB at 800 or 1066. Typically this was twice what the actual host frequency was, so a processor would have a multiplier based on the actual host clock.

Example: The Intel Core 2 Extreme QX9770 runs at 3.2 GHz, and claims a "1600 MHz" FSB. This is a "Quad-pumped" FSB and the host clock is truly running at 400 MHz, still extremely fast. So the multiplier of this processor is 8.

Host clock * Multiplier = Clock Speed

400 MHz * 8 = 3200 MHz, or 3.2 GHz.

Introduction - The "New" Way

But "Nehalem" changes everything. Much like AMD did with their initial launch of the Athlon64 years ago, Intel has finally moved the memory controller onto the processor itself.

Here's how the new way works.

THE NEW WAY - QUICKPATH INTERCONNECT

The FSB has been removed completely - the memory controller and processor now have very little delay. This allows much lower latency and provides a significant increase in computing performance.

How significant? Let's find out....

The Build - Processor and Motherboard

First things first, let's compare a Nehalem Processor - known as the Core i7 - to an older Quad-Core, the Yorkfield processor.

As you can see, the QX9770 pictured on the right is physically smaller and contains many fewer pins than the Core i7 965 on the left.

However, the front isn't so different. Our processor is an engineering sample, which is why the logo on the front says Intel Confidential. Retail products will have the part number on them.

As you may have deduced by now, a new processor design requires a new socket, and a new socket requires a new motherboard. We've chosen Asus's P6T Deluxe.

Asus has a great reputation in the industry for providing rock solid overclocking boards, and we're using this one for a couple of reasons. For one, the only Nehalem compatible chipset, (Intel's X58 chipset) is tough to find right now, and this board was available. Secondly, our initial results in the lab while testing memory on this board were very positive.

The new socket is called LGA1366, or Socket B. This replaces LGA775, or Socket T, which Intel has been using since the Pentium 4 days.

Here's a quick shot of what the new socket looks like.

As you can see, it's fairly similar to the LGA775 socket, just larger. It will require a new heatsink mounting mechanism, though. So if you're planning on using a 3rd party heatsink, like we did, you should request the mounting hardware from the manufacturer.

DHX+ - Three Way Memory

Now the cool part of Core i7 is not just that it's got an onboard memory controller. That's cool, sure.

The real cool part is that it's got a triple-channel onboard memory controller. That's three channels of memory for optimum bandwidth.

Meaning six slots of RAM.

Check this out.

See that? Six slots. Three channels. You could easily install up to 12GB of RAM in that right now. That's pretty sexy.

But what's the sticker say? Well, because Intel's put the memory controller on the CPU, they advise against high VDIMM, or memory voltage. Anything over a 10% increase (from 1.5V to 1.65V) they say could be potentially hazardous to the processor. This is something overclockers have known for quite a while - increasing voltage shortens the lifespan of your products.

Nonetheless - most of Corsair's triple memory kits are rated at 1.65V or lower.

Including the kit we're using - the 1866C9 6GB kit.

Three 2GB modules rated at 1866 MHz @ 9-9-9-24 latencies, optimized for Nehalem. But wait, what's the new heatsink all about?

Corsair invented the world's first true memory heatsink with the Dominator with DHX technology. We're now talking about the Dominator with DHX+ technology. New fins, new heatsinks, and the same great technology exists for our modules - only now, there's more flexibility. We'll see more about that very soon.

But what about cooling them? Nehalem boards have six slots and the Dominator Airflow can't fit over all six, can it?

Looks like it can. The new Airflow is optimized for Nehalem with two 60mm fans that spin at a very low noise level. The best performance you can get out of the box, bar none.

Let's build it...

Let's talk a second about the last few components...

The new Western Digital Velociraptor hard drive, a 2.5" 10,000 RPM drive in a 3.5" heatsink enclosure. SATA II, 300GB of pure, angry speed. A great drive to use for a system build.

The Corsair HX1000W PSU, of course. The best PSU in the industry right now, and the first 1000W PSU to get certified for 3-way SLI. A rock-solid part with industrial grade components.

Add these together with a Thermalright Ultra 120 Extreme....

Plug in the memory.... (we're using orange slots here for Channels A, B, and C)

Snap on the Airflow fans and power the system on...

And install everything into one of our favorite cases, the Silverstone TJ07B.

Now that we've got all that done, let's get to the meat of it...

The BIOS

First things first, every new motherboard has a new BIOS to learn.

This one is no exception, but there's some interesting things we should talk about, and we'll go through them one at a time.

This is the main BIOS screen, it's pretty self-explanatory and common. Nothing too different here, if you're familiar with Asus boards. It's a typical AMI Bios.

But here's where it gets interesting. The AI Tweaker section is where we'd go to overclock anything, and there are some new things on this list we should look at.

For example, you can see "CPU Ratio Setting" is highlighted. This allows us to modify the multiplier of the processor should we need to. Since Nehalem doesn't have a FSB, it uses a host clock, and thus Nehalem processors have much higher multipliers.

The processor we're using, a Core i7 965, has a 24x multiplier for a host clock of 133 MHz. 133 x 24 = 3.2GHz clock speed.

And of course, the QuickPath Interconnect (QPI) speed.

This should be as high as possible - the fast this runs, the more your CPU can do. However, this is going to be dependent on how fast the processor is running, so in order to get a great overclock, you might have to drop this down just a bit. Keep that in mind as you go through your settings.

On to overclocking....

The first thing we have to do is turn the Overclock Tuner to Manual

This allows us to change the other settings. For example, the host clock.

The Host Clock is the soul of your overclocking attempt. If you are trying to get a good overclock, start here.

Say you have a Nehalem processor at 2.66 GHz. This would be a 20x multiplier and a 133 MHz Host Clock.

Remember before, the FSB in older systems? Same concept here.

Host Clock * Multiplier = Frequency

133 MHz * 20 = 2660 MHz or 2.66 GHz.

If we were to raise that host clock to 150 MHz....

150 MHz * 20 = 3000 MHz or 3.00 GHZ

So anytime you're going to overclock a Core i7, keep the Host Clock in mind, it's where you'll start.

DRAM Frequencies and Performance

DRAM frequency. Since memory bandwidth has increased significantly, having faster DDR3 memory actually makes a huge difference with Nehalem. How much?

But having fast memory doesn't work by itself. It's going to need to be tweaked.

First things first, we'll have to hit DRAM TIMING CONTROL and change the latencies.

Since our DDR3-1866 kit is rated at 9-9-9-24, we've gone ahead and changed that.

Next, we need to work on the Voltage.

Remember, higher than 1.65 isn't recommended by Intel, the closest this BIOS allows is 1.66, so we're going to go with that. Once we've done this, we'll go ahead and reboot into Windows.

I ran a couple of tests to give you an idea of the performance.

First things first, here's our CONTROL SYSTEM

Processor: Intel Kentsfield QX9850 (3.0 GHz)
Memory: 4GB DDR3-1333 @ 9-9-9-24 (dual channel)
Motherboard: Asus P5E3 Deluxe

Here's the Everest read/write performance numbers for a baseline.

Now let's talk about our NEHALEM SYSTEM

Processor: Intel Core i7 965 (3.2 GHz)
Memory: 6GB DDR3-1866 @ 9-9-9-24 (triple channel)
Motherboard: Asus P6T Deluxe

Here's the Nehalem at the exact same memory settings (DDR3-1333)
everest - nehalem1.png

Here's the Nehalem at the advertised memory settings (DDR3-1866)

everest - nehalem2.png

Look at those huge increases! Performance numbers through the roof!

Just for curiosity's sake, let's look at another one....

These are numbers taken from SiSoft Sandra 2009! Look at the huge increase in bandwidth!

The latency numbers are equally impressive.

Truly, the Core i7 looks like a monster.

FPU/Gaming Performance

There are going to be all sorts of gaming performance reviews out soon, and plenty around the net to take a look at. Here's some interesting data from 3DMark06.

Kentsfield system with NVIDIA GeForce GTX280

Nehalem system with NVIDIA GeForce GTX280

The performance difference is significant. In the coming days, we'll see a lot more benchmarks and performance numbers from Nehalem, but one thing's for sure - the performance benefit is very real, and it's huge.

Intel's done it again, and this new platform combined with the plummeting costs of DDR3 over the last year make it an attractive buy for the enthusiast and a must-buy for the performance junkie.

AMD and Intel

Corsair Labs : Intel Core i7 Build & Architecture Changes

Introduction - The "Old" Way

Introduction - The "New" Way

The Build - Processor and Motherboard

DHX+ - Three Way Memory

Let's build it...

The BIOS

DRAM Frequencies and Performance

FPU/Gaming Performance

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