Core i7 is Amazing When All Cores Are Running, but How Do Single Thread Apps Hold Up?
In a word: Well. They won’t blow your socks off the way they will when octa-threading, but all reviews are reporting modestly improved performance from the 965XE over the QX9770 even if most of your threads are twiddling their transistors. For example, four of the reviewers mentioned above (Hexus didn’t include this result) reported increases of 7%, 12%, 10% and 15% when running the single thread version of Cinebench.
The breadth of the numbers is because some people tested with Turbo Boost on to show how the CPU would really perform, while others tested with it off so they could compare the QX9770 and 965XE at an unvarying 3.2 GHz. Turbo Boost automatically overclocks busy cores by 133 or 266 MHz when other cores are idle. It looks like the difference in single thread performance is due in almost even proportion to clock for clock (i.e.: both chips running at the same 3.2 GHz) speed improvements and the Turbo Boost overclocking.
The Core i7 improvements weren’t enough to keep the lower clocked 940 and 920 out in front though. The QX9770’s higher clock vs. the lesser i7s is usually enough to overcome its age when only one core is involved. Then again, it is a much more expensive chip and any one of the i7’s spanks it on a per dollar basis.
The real shockers came courtesy of Hardware Canucks and Tech Report who respectively included the E8400 and E8600 Core 2 Duos in their reviews. When you are down to one core, the massive clocks for little money these chips offer becomes very attractive. In single-thread Cinebench, the E8400 and E8600 actually rank between the 920 and 940.
The obvious question is: Who cares about how something runs in single thread mode if you will always use it in multi-thread mode? Fair enough, many if not most professional and productivity applications are meant to take advantage of multi-threading. Games though, are only beginning to reap these rewards, as revealed in the next article.