Intel - Core i5 661 review
Intel Clarkdale has graphics in the CPU core
Review date: 20 January, 2010. Review by: IT Reviews Staff
Core i7 900 (development name Nehalem) introduced us to Intel's integrated memory controller which was combined with a quad core processor that used Hyper Threading to create eight virtual CPU cores. Then we saw Intel's Lynnfield technology used in Core i7 860/870 and Core i5 750 that moved the PCI Express controller from the chipset to the processor core. The result is that the P55 chipset is actually a single chip that handles the traditional Southbridge USB, SATA, audio and networking functions.
Now we have Clarkdale which uses the same LGA1156 processor socket that was introduced with Lynnfield, along with the same dual channel DDR3 memory controller, but there have been major changes inside the CPU core. The fabrication process has changed from 45nm to 32nm, which is a major move in itself, but that's only part of the story.
Intel has moved the graphics package from its traditional location in the Northbridge of the chipset to the CPU package, and beneath the heat spreader there are two separate chips instead of the usual one.
It is traditional for chipsets to lag one or two fabrication processes behind CPUs so although the Core i5 661 uses the new 32nm process the graphics package is fabricated on 45nm.
The most recent Intel chipset with integrated graphics is the G45 for Core 2 with GMA X4500 graphics which uses a 65nm process. It's quite a big leap from 65nm to 45nm, however the technology in the graphics package has made relatively modest advances from the G45 core and still supports DirectX 10.0 and Shader Model 4, although Open GL support has been increased from 2.0 to 2.1.
The number of Unified Shaders has been increased from 10 to 12 but the clock speed has been reduced from 800MHz to 733MHz on most models (Core i3 530/540, Core i5 650/660/670) while the Core i5 661 is clocked at 900MHz. Curiously enough Intel selected the Core i5 661 to send to reviewers.
This increase in graphics clock speed has a marked effect as the five slower Clarkdale CPUs have a TDP of 73W while the Core i5 661 has a TDP of 87W.
Other changes to the graphics include support for dual digital displays with resolutions of 2,560 x 1,600 along with a number of features that should appeal to the Home Theatre brigade such as eight-channel audio at 24-bit/96kHz, support for Dolby TrueHD and DTA-HD Master Audio codecs and full hardware decoding for H.264, VC1 and MPEG2.
We tested the graphics with 3DMark06 and obtained a score of 2,000 marks which eclipses the 1,400 marks you will see when using a G45 chipset in conjunction with a Core 2 Duo. The increase in the score is a combination of a number of factors including the strength of Core i5 with its dual cores and Hyper Threading, the integrated DDR3 memory controller, the extra Unified Shaders, the increased graphics clock speed and the shortened communication path. It's our opinion that the graphics in Core i5 661 are as good as Nvidia's ION.
If you fancy a spot of gaming you'll need to install a graphics card in your Clarkdale PC but that's an open option as motherboards that sport a new Q57, H55 or H57 chipset are very likely to have a PCI Express 2.0 graphics slot.
The point to remember is that the PCI Express controller is in the CPU and not in the chipset. Any sensible motherboard manufacturer will include a graphics slot as you might choose to install a Lynnfield Core i7 (without a graphics package) in an H55 motherboard which means that you'll require a graphics card even though the motherboard includes HDMI, DVI and VGA connectors. Confused? We have a horrible suspicion that there will be a fair few people upgrading PCs who fall into some obvious pitfalls.
Incidentally the new Clarkdale chipsets are called PCH or Platform Controller Hub as the old designations of ICH and MCH have become somewhat redundant.
The performance of Core i5 661 is everything that you'd expect from a dual core CPU with Hyper Threading that is clocked at 3.33GHz. The Turbo Boost features raises the clock speed to 3.60GHz and if you overclock your new CPU you should have no trouble running it at 4.2GHz.
Ironically we feel that the biggest problem faced by Core i5 661 comes from Core i5 750, which is clocked slower at 2.66GHz but which has four hardware cores with no HT. When you load your CPU by editing videos or playing games you'll find that Core i5 750 delivers better results than Core i5 661.
Core i7 661 looks like good value and would make a superb foundation for a highly integrated PC, but we suspect that the slower, cheaper Core i3 will prove more popular.
Verdict
Core i3 and Core i5 CPUs with the new Clarkdale core take a significant step towards the mythical system-on-chip where the functions and features are delivered by a single chip, rather than the traditional CPU, chipset and GPU. As things stand you'd be hard-pressed to tell the difference between a Core i5 661 PC and a Core 2 or Core i7 PC, so the prospect of a small, cheap, powerful PC remains somewhere in the distance.
Company: Intel
Contact: 01793 403000
