AMD Phenom II X4 940 & 920: A True Return to Competitionby Anand Lal Shimpi on January 8, 2009 12:00 AM EST
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Clock for Clock, Still Slower than Core 2 & Core i7
It was important on the last page to point out that the predominant difference between Phenom and Phenom II is the larger L3 cache; although there are minor architectural tweaks we're fundamentally looking at a core that remains very similar to the Phenom it replaced. The larger L3 cache helps Phenom II stay fed more frequently without painful trips down main memory lane, but Intel's architectures should still be faster at the same clock speed. To prove that point let's look at the following data. It's a subset of the benchmark suite for this article and what we've got below is Phenom II, Core i7, and Core 2 Quad all running at 3.0GHz (the Core i7 runs at 2.93GHz):
|Processor||Clock Speed||Adobe Photoshop CS4 (lower is better)||x264 Pass 2||3dsmax 9||Cinebench||SYSMark 2007 Overall||Left 4 Dead||FarCry 2|
|AMD Phenom II X4 940||3.0GHz||24.2 s||17.8 fps||10.8||12393||182||116.2 fps||48.2 fps|
|Intel Core 2 Quad Q9650||3.0GHz||19.4 s||19.9 fps||12.0||12983||209||125.2 fps||61.9 fps|
|Intel Core i7-940||2.93GHz||15.8 s||29.2 fps||16.2||17346||229||123 fps||71.0 fps|
|Core 2 Quad Q9650 Advantage||-||19.8%||11.8%||11.1%||4.8%||14.8%||7.7%||28.4%|
|Core i7-940 Advantage||-||34.7%||64%||50%||40%||25.8%||5.9%||47.3%|
|Core 2 Quad Q9650 Disadvantage||$265|
|Core i7-940 Disadvantage||$295+|
Clock for clock, Intel has the advantage across the board. It gets very close between Phenom II and Penryn (Q9650) under Cinebench, but 3dsmax 9 shows a wider gap of 11% between the two. Gaming also looks pretty close if you look at Left 4 Dead; however, Far Cry 2 (a newer engine and much more heavily threaded game) is on the opposite end of the spectrum. The take away point is that compared to Penryn, Phenom II is slower clock-for-clock. The gap grows with Nehalem; Phenom II only gets close in older game engines, while the rest of the time Nehalem is 30-60% faster at the same clock speed.
What matters isn't just absolute performance however, it's performance at a given price point. The last two rows tell an important story; while Intel is faster at the same clock speed, the CPUs themselves cost twice as much as AMD's Phenom II. Nehalem's cost premium is even higher as X58 based motherboards are still above $200, plus they require DDR3 memory. It doesn't matter that AMD won't win the absolute performance crown with Phenom II; like the Radeon HD 4800 series, what's important here is whether or not AMD is competitive at the performance mainstream price points. It's this question that we'll be answering over the course of today's review.
Core i7: Total Cost of Ownership
While Intel's Core i7 is undeniably the fastest CPU on the market today, it comes at a steep cost. The i7 920 is competitively priced at $295, and outperforms the Phenom II X4 940 across the board, but it will only work with DDR3 memory and requires an X58 motherboard - and those are currently selling for no less than $200. The table below summarizes the problem with comparing Nehalem to Phenom II:
|AMD Phenom II X4 940||$275||$120||$75||$470|
|Intel Core i7-920||$295||$210||$150||$655|
|Intel Core 2 Quad Q9400||$270||$100||$75||$445|
Despite the similar CPU costs, the motherboard and DDR3 memory costs make the i7-920 a 40% more expensive purchase. For the difference in platform cost you could purchase a faster graphics card, bigger hard drive, or even put money towards an SSD. Core i7's total cost of ownership keeps it from being Phenom II's direct competition; instead Phenom II is really competing with Intel's 45nm Core 2 Quad processors.
While X58 motherboards will always be pricey thanks to the high-end chipset costs (the minimum pricing we're hearing is $185), DDR3 prices should fall over time, especially once AMD starts moving over to DDR3 in the coming months. Right now DDR2 is incredibly affordable, working in AMD's favor.
With Core i7 out of the running, our eyes turn to Core 2 Quad as Phenom II's intended competition. The table above hints at the Q9400 as Phenom II's competition today, but let me flesh things out a little more:
|Processor||Clock Speed||Cache||1K Unit Cost|
|Intel Core 2 Quad Q9650||3.00GHz||12MB L2||$530|
|Intel Core 2 Quad Q9550||2.83GHz||12MB L2||$316|
|AMD Phenom II X4 940||3.0GHz||2MB L2 + 6MB L3||$275|
|Intel Core 2 Quad Q9400||2.66GHz||6MB L2||$266|
|AMD Phenom II X4 920||2.8GHz||2MB L2 + 6MB L3||$235|
|Intel Core 2 Quad Q8300||2.50GHz||4MB L2||$224|
|Intel Core 2 Quad Q8200||2.33GHz||4MB L2||$193|
|Intel Core 2 Quad Q6600 (65nm)||2.40GHz||8MB L2||$183|
Other than the Q6600, all of the CPUs in the above chart are 45nm parts (congrats AMD). But look at where the Phenom II slots in. The Phenom II X4 940 is slightly more expensive than a Q9400, while the 920 is a Q8300 competitor. With Core i7's platforms pricing it out of the comparison, the table above should indicate what you need to look at when comparing Phenom II and Core 2 Quad.
I'll mention this briefly here (and more later). Pay close attention to the Q9650 and Q9550. Intel has the ability to move those down the price list, whereas the Phenom II X4 940 is going to be the fastest Phenom II out for the next couple of months.
Ok, I lied, Intel Spoils the Party. Rumored Intel Price Cuts
At the end of last year Intel made some minor price cuts across its product lineup. There was no reason to do anything more serious as AMD hadn't even begun to threaten anything above the Core 2 Quad Q6600.
I've heard, through reliable but very quiet channels, that before the end of January Intel will aggressively cut prices on its entire quad-core lineup. Given how Intel historically cuts prices, we could expect the Core 2 Quad Q9550 would take the place of the Q9400 and have the Q9400 move down to the price point of the Q8300, thus creating a price war; and you thought 2008 was the last of that.
If Intel were to push its prices down like that, the Q9550 would compete with the Phenom II X4 940, and the Core 2 Quad Q9400 would go up against the Phenom II X4 920 instead. If this happens, the conclusion I mentioned on the first page changes. The Phenom II X4 940 can't beat the Q9550, and the 920 can't beat the Q9400. Intel has the ability to do this; it's got faster chips that are more expensive and has just enjoyed 2+ years of unchallenged competition. The Intel from the Pentium 4 days may have let AMD launch Phenom II unchecked, but today's Intel is much more...dynamic.
The take away is that today Phenom II competes with the Q9400 and the Q8300, but by the end of this month that may change to the Q9550 and Q9400.