In the first part of this article, we covered the design of Intel's new integrated CPU + iGFX, combining a Westmere dual core die with a 3rd generation integrated graphics processor on the same package. The pinout is slightly modified compared to the Lynnfield platform, featuring one extra pin to bring the total pin count up to 1156 (to signal the presence of the graphics processor) yet maintains overall cross-compatibility with the Lynnfield platform.

In this second part we are looking at the performance of Clarkdale with special emphasis on the synergism between the two separate processors, namely the borrowing of CPU cycles for graphics processing, and were it applies - or not.

The real thing: Intel Core i5-661 "Clarkdale"

Test Configuration and Power Measurements

We tested the Intel Core i5-661 in the following system configuration:

• Motherboard: Intel DH55TC
• Memory: OCZ3ALVE16004GK
• CPU: Intel Core i5-661
• Cooler: Intel Stock
• Graphics Card: ASUS EAH5850 (discrete graphics)
• HDD: HDD: WD 1500ADFD (Raptor)
• SSD: Intel SSDSA2MH080G15E (80 GB)
• Optical Drive: HP dvd1070i-H01 6 Multiformat DVD writer
• PSU: OCZ Modstream 600ADJ
• Monitor: Acer H233H

** The memory was run at 1066 MHz 8-8-8

Intel DH55TC

The only gripes we had with this particular motherboard was that the "keyboard" port did not work, we had to use a USB converter to interface with the Microsoft keyboard used, and the lack of memory adjustments forcing us to run perfectly fine memory at 1066 MHz. For Comparison of the integrated graphics, we ran the following system configuration:

• Motherboard: MSI 785GM-E65
• Memory: OCZ3ALVE16004GK
• CPU: AMD Athlon II X4 630, Phenom II X4 965 BE
• Cooler: OCZ Vendetta 2
• Graphics Card: ASUS EAH5850
• HDD: HDD: WD 1500ADFD (Raptor)
• SSD: Intel SSDSA2MH080G15E (80 GB)
• Optical Drive: HP dvd1070i-H01 6 Multiformat DVD writer
• PSU: OCZ EvoStream (720W)

** The memory was run at 1333 MHz 8-8-8

Benchmark Overview

• Windows 7 64 Ultimate Edition, Win XP-32 SP3*
• CPU-Z 1.52
• Caligari TrueSpace 5.1
• Caligari TrueSpace 7.5
• Cinebench R10
• Cinebench 9.5
• Crysis
• DIEP Chess
• DVD-Shrink
• FarCry2
• Futuremark 3DMark Vantage
• Race Driver GRID ebay Motors Muscle Series
• MainConcept H.264
• Microsoft Excel 2007
• Unreal Tournament3
• VirtualDub + DivX 6.8.5 CODEC
• World-In-Conflict
• SiSoft Sandra
• Unigine "Sanctuary", "Tropics" and "Heaven"

Some of the benchmarks used do not run on Windows Vista and subsequent Microsoft OS releases because of DRM issues. For this reason, most of the benchmarks were run on a Windows XP OS (which still has a market share of approximately 67%. All high-resolution gaming benchmarks were run on Windows 7 Ultimate 64-bit.

Power Measurements

Looking at system power consumption is interesting to a certain degree, however, for all practical purposes we are more interested in the isolated CPU power consumption. To estimate the latter, we used the same power measurement setup as in previous reports. Briefly, we used a Fluke 80i-410 AC/DC current probe in combination with a Wavetek Meterman 30XR multimeter to measure current through the isolated +12V supply lines feeding into the CPU VRM. To increase granularity of the measurements, we ran the supply lines in a triple loop through the clamp. The clamp itself was calibrated using a BK Precision model 1692, 30V 40 A DC power supply. Since there is a temperature dependency of the probe, we monitored the zero-current offset at the beginning of each measurement as well as at the end of each run. If the values drifted we retook the measurements. Despite these precautions there are possible deviations of the read-out from the real current, however, these errors mostly affect the lower (processor idle) measurements. We estimate that the errors should not be more than 10% at the lower end of the data and less than 5% in the mid and higher data range. Moreover, since the same procedures were applied to all processors tested, there may be an offset in the absolute numbers, however, the relation of the individual cores to each other with respect to power consumption should be fairly accurate.

Having learned our lessons regarding power measurements on the Nehalem platform, we verified that the 4+1 phases of the VRM receive their power from the 12V auxiliary power plug by ohming out the connections between the MOSFETs and the plug on one side and the MOSFETs and CPU socket on the other side. In theory, showing the electrical continuity does not exclude additional supply power coming in from the 24 pin main eATX connector, however, we also checked there and got "open circuit" readings. This means that we can with reasonable certainty claim that the entire CPU power, including cores and NB/IMC (but excluding I/O power) is derived exclusively from the auxiliary 4-pin 12V input. Details are given on this page.

In addition to the method outlined above, we used a modified PSU to run the 12V line directly through the Wavetek Meterman and read out the current. Both methods gave identical results.