AMD's Six-Core Phenom II X6

A very smart man once told me that absolute performance doesn’t matter, it’s performance at a given price point that makes a product successful. While AMD hasn’t held the absolute performance crown for several years now, that doesn’t mean the company’s products haven’t been successful.

During the days of the original Phenom, AMD started the trend of offering more cores than Intel at a given price point. Intel had the Core 2 Duo, AMD responded with the triple core Phenom X3. As AMD’s products got more competitive, the more-for-less approach didn’t change. Today AMD will sell you three or four cores for the price of two from Intel.

In some situations, this works to AMD’s benefit. The Athlon II X3 and X4 deliver better performance in highly threaded applications than the Intel alternatives. While Intel has better performance per clock, you can’t argue with more cores/threads for applications that can use them.

When Intel announced its first 6-core desktop processor, the Core i7 980X at $999, we knew a cheaper AMD alternative was coming. Today we get that alternative, this is the Phenom II X6 based on AMD’s new Thuban core:

It’s still a 45nm chip but thanks to architecture and process tweaks, the new Phenom II X6 still fits in the same power envelope as last year’s Phenom II X4 processors: 125W.

Update: AMD tells us that it gave us the wrong pricing on the 1090T. The part sells for $295, not $285, in 1000 unit quantities.

CPU Specification Comparison
Processor	Clock Speed	Max Turbo	L2 Cache	L3 Cache	TDP	Price
AMD Phenom II X6 1090T	3.2GHz	3.6GHz	3MB	6MB	125W	$295
AMD Phenom II X6 1055T	2.8GHz	3.3GHz	3MB	6MB	125W	$199
AMD Phenom II X4 965 BE	3.4GHz	N/A	2MB	6MB	125W/140W	$185
AMD Phenom II X4 955 BE	3.2GHz	N/A	2MB	6MB	125W	$165
AMD Phenom II X4 945	3.0GHz	N/A	2MB	6MB	95W	$155
AMD Phenom II X4 925	2.8GHz	N/A	2MB	6MB	95W	$145

You also don’t give up much clock speed. The fastest Phenom II X6 runs at 3.2GHz, just 200MHz shy of the fastest X4.

When Intel added two cores to Nehalem it also increased the L3 cache of the chip by 50%. The Phenom II X6 does no such thing. The 6 cores have to share the same 6MB L3 cache as the quad-core version.

There’s also the issue of memory bandwidth. Intel’s Core i7 980X is paired with a triple channel DDR3 memory controller, more than enough for four cores under normal use and enough for a six core beast. In order to maintain backwards compatibility, the Phenom II X6 is still limited to the same dual channel memory controller as its quad-core predecessor.

CPU Specification Comparison
CPU	Codename	Manufacturing Process	Cores	Transistor Count	Die Size
AMD Phenom II X6 1090T	Thuban	45nm	6	904M	346mm2
AMD Phenom II X4 965	Deneb	45nm	4	758M	258mm2
Intel Core i7 980X	Gulftown	32nm	6	1.17B	240mm2
Intel Core i7 975	Bloomfield	45nm	4	731M	263mm2
Intel Core i7 870	Lynnfield	45nm	4	774M	296mm2
Intel Core i5 670	Clarkdale	32nm	2	384M	81mm2
AMD Phenom II X4 965	Deneb	45nm	4	758M	258mm2

The limitations are nitpicks in the grand scheme of things. While the 980X retails for $999, AMD’s most expensive 6-core processor will only set you back $285 and you can use them in all existing AM2+ and AM3 motherboards with a BIOS update. You're getting nearly 1 billion transistors for $200 - $300. Like I said earlier, it’s not about absolute performance, but performance at a given price point.

AMD 2010 Roadmap
CPU	Clock Speed	Max Turbo (<= 3 cores)	L3 Cache	TDP	Release
AMD Phenom II X6 1090T	3.2GHz	3.6GHz	6MB	125W	Q2
AMD Phenom II X6 1075T	3.0GHz	3.5GHz	6MB	125W	Q3
AMD Phenom II X6 1055T	2.8GHz	3.3GHz	6MB	125W/95W	Q2
AMD Phenom II X6 1035T	2.6GHz	3.1GHz	6MB	95W	Q2
AMD Phenom II X4 960T	3.0GHz	3.4GHz	6MB	95W	Q2

We'll soon see more flavors of the Phenom II X6 as well as a quad-core derivative with 2 of these cores disabled. As a result, motherboard manufacturers are already talking about Phenom II X4 to X6 unlocking tools.

The new Phenom II X6 processors are aimed squarely at Intel’s 45nm Lynnfield CPUs. Both based on a 45nm process, AMD simply offers you more cores for roughly the same price. Instead of a quad-core Core i7 860, AMD will sell you a six-core 1090T. Oh and the T stands for AMD’s Turbo Core technology.