Intel i5 661 3.33GHz Dual Core CPU

Introduction

It's that time of year again, Christmas is in the air, the smell of pine trees gracing the lab, CES just around the corner, and above all else the smell of a new CPU going through burn in testing on the test rig.

Intel was nice enough to send in one of their LGA 1156 i5 661 32nm dual core CPU's that run at a blistering 3.33GHz out of the box. They also sent in an LGA 1156 DH55TC motherboard which is primarily designed for HTPC/Media applications. We'll be taking a look at both with the primary focus on the CPU with it's newly integrated graphics that sit on the processor itself. Yes Intel has delivered a CPU with graphics integrated on the CPU.

We can hear the groans from the serious enthusiasts already, "Oh no integrated graphics". Well we were a little skeptical ourselves until we ran it. It's not a powerhouse integrated graphics but it's more than adequate for Blu-Ray playback, light gaming, and most end users won't need anything more powerful than the integrated graphics built into the chip. That's saying a lot for an integrated graphics solution. We also ran the i5 661 in a high end Asus Maximus 3 board with a discrete GPU to see if the integrated graphics were going to interfere with discrete GPU usage and had no problems with running several discrete GPU's we tried so if integrated graphics isn't what you need the i5 661 will allow you to go to a discrete GPU. Before you think discrete GPU though you might want to look at the 3DMark Vantage results on the Intel HD integrated graphics.

Seen here just like we received it (mounted on the DH55TC board) you should know there is nothing like the smell of a new motherboard with an Intel confidential CPU roasting on it. Of course we mounted the CPU cooler before roasting it but you get what we mean.

Lets take a look at the H55 Express chipsets block diagram.

The new i5 661 3.33GHz CPU is based on a 32nm design and for the first time the 32nm designed CPU will be widely available at launch. Traditionally new process releases from Intel follow the same pattern, they release an Extreme edition/enthusiast chip first in lower quantities. The i5 661 isn't being released like that, it's more mainstream and even though it features the new 32nm process it will be widely available at launch, this is a good indication that the 32nm is a fairly robust process. In other words the manufacturing process is well designed and the yields are high enough that Intel can release much larger quantities immediately.

The DH55TC board we received is primarily designed for HTPC/Media usage and the BIOS was pretty rudimentary. We had no control over Memory speed, timings, or voltages and the board set the memory to 1333 with cas 9 timings. We don't know if later a more mature BIOS will allow for those features. We also had to struggle with nothing more than one overclocking setting total. They allowed for changing the Bclk on the CPU but it appeared like it was added as an afterthought because we had no control over CPU voltage, PCH voltage or any other pertinent OC setting. Since the board is designed for HTPC/Media applications we didn't expect much in the way of OCing amenities.

As you can see in the Block diagram the i5 661 CPU provides for 16 PCI-E 2.0 lanes and 1333MHz memory. The PCH provides for the ports to connect your monitor to, 12 USB 2.0 high speed lanes, the 10/100/1000 MAC that drives the Gigabit LAN port, firmware support and BIOS support.  The PCH also provides for Intel HD audio, six PCI-E 1x lanes, and six SATA 2.0 ports as well as E-Sata, it also provides the ability to turn off those ports.

The i5 661 has:

• 383 Million transistors for the CPU itself
• CPU Process is 32nm
• CPU Die size 81mm squared
• CPU is Hyperthreaded (2 physical cores 4 virtual cores)
• CPU speed 3.33GHz
• 117 Million transistors for the integrated Intel HD Graphics Gfx
• Gfx Die size is 114mm squared
• Gfx process is 45nm

Hmmm that got us to thinking integrated graphics on the CPU die but two specifications for die size and they use a different process (32 and 45nm) for both. So we had to dig into the Intel FTP site for more information.

Sure enough we found a naked shot of the CPU/Gfx chip. The smaller CPU is on the left of the Die and the Gfx chip is on the right side of the die. To the right of the CPU is the PCH (Platform Controller Hub). So the Gfx chip isn't inside the CPU itself but shares the same die which makes sense and given the massive success of Intel's older double cheeseburger design on CPU's like the Q6600 where they placed two dual cores on one die Intel has the know how to make a CPU and Gfx chip coexist peacefully on the same die. Makes one wonder if down the line we'll be seeing the Gfx chip inside the CPU itself.

We left all the settings at stock on the Intel DH55TC motherboard and fired up Prime95 to do a little burnin prior to benchmarking. One of the newer featuress on i7/i5/i3 Intel processors is Turbo Boost, the top end non-Turbo Boost multiplier on the i5 661 is 25 which should be great for OCing friendly boards (25 Mult X 200Bclk = 5GHz) so most boards should be able to push this jewel to the limits and beyond. Almost all the boards we've seen easily hold a 200 Bclk and with a sky high CPU multiplier of 25 the i5 661 is sure to be a legendary overclocker.

CPU-Z is reading the 32nm process used on the i5 661 correctly, reports 1.144v for the load voltage under Prime 95 stress testing, and Turbo Boost has the CPU multiplier at 26 and the Bclk at the default 133MHz yielding a 3.467GHz speed at default settings in BIOS.

The L1 data cache is 2x32KB, the L1 instruction cache is also 2x32KB, the L2 cache is 2x 256KB, and the level 3 shared cache is 4MB total. We'll show you why we pictured both CPU screens on top the photo in just a second.

The motherboard tab is showing the Intel DH55TC board correctly but on the memory tab we get the memory timings but not the memory speed so CPU-Z has a little catching up to do for the new chip.

We stopped Prime 95 and got this screen shot of CPU-Z at just the right moment to catch the CPU's downshifting speeds. The CPU shot on the top left pane is 1.862GHz and on the right pane it's showing 1.463GHz. In all reality this happens so fast that we were lucky to get the shot of it downshifting. Notice that at an idle the power saving feature kicked in and lowered the multiplier to 11 and the voltage to 0.944v.

Here's some information we got from Intel on the Intelligent Performance features of the i5 661:

Intelligent performance: As you saw with Lynnfield and Clarksfield (the latest Core i5/i7s), this concept of delivering the pure speed you know us for PLUS “intelligent performance” is huge with our product line. Turbo Boost is there for lightly or non-threaded applications, and threading is there for highly threaded workloads.  Our latest Core i5/i7 processors intelligently adapt based on how YOU are using the system – you will see us market these chips as ready for mainstream, and first-ever that intuitively adapt to an individual’s needs. Turbo, multi-threading, HUGI battery-saving technologies and even Adaptable Switching that lets you toggle between our integrated graphics and if needed discrete graphics helps us pack a lot of ‘smart’ inside a chip ready for widespread purchase/adoption.

This is one of the features we firmly believe in, the CPU shifts performance according to your needs. While hardcore overclockers will disable a lot of the power savings features out of habit we've actually overclocked the i7/i5 series and left power savings enabled and done it with great success. You do have to allow for the 1x multiplier increase in turbo when overclocking as far as the thermal envelope of your CPU cooler goes. Say your pushing the thermal envelope on your cooler at 25x CPU multiplier at 200Bclk and driving this beauty at the ragged edge of performance then the Turbo Boost feature trys to kick in and suddenly your at CPU Mult 26 and you hit 5.2GHz. The added 200MHz might exceed your thermal envelope and trigger throttling on the CPU. Our Maximus board let us set the multiplier to 26 manually avoiding that but you would need to check and see if your board will manually set it to 26. We don't think that will be much of an issue with the i5 661.

This isn'tthe best OC we got but we have the i5 661 running on the Asus Maximus board, Prime 95 running for 5 minutes and both cores (Hyperthreading enabled so 2 cores but 4 virtual cores) chugging as hard as they can go. The Bclk is set to 160, CPU Mult 26, Voltage a tad under 1.3v and we got 4.177GHz insanely easy. Thermal build up at 4.177GHz after 5 minutes was only 48° C leaving pretty good overhead for more insane overclocking.You should be aware that we did this run with a Thermalright Mux 120 and not stock cooling. We did get as high as 3.75GHz on the Intel board with stock cooling and that should tell you this is a cool running CPU in comparison to the hyperthreaded quads we are used to seeing.