The new CPUs
Clock speeds: 2.6GHz (FX-70), 2.8GHz (FX-72), 3.0GHz (FX-74)
In many ways AMD’s new 4x4 CPUs (the Athlon 64 FX-70, FX-72, and FX-74), share more in common with AMD’s server-oriented Opteron line of CPUs than the Athlon 64 X2. Considering the origins of the FX line (and the Athlon 64 in general for that matter) date back to the Opteron, you could say that the new FX-7x CPUs are going back to their roots, but more on that later. Let’s take a look at the new CPU specs:
128K L1 cache per processing core (64K instruction, 64K data); 256KB total L1 cache per processor
1MB L2 cache per core; 2MB L2 cache per processor
Shared integrated 128-bit wide memory controller
DDR2-800, DDR2-667, DDR2-533, DDR2-400 Unbuffered Memory Supported
Two 16-bit HyperTransport links at 2GHz (2x1000MHz DDR)
Effective Data Bandwidth: 33.6GB/sec (8GB/sec HyperTransport link + 25.6GB/sec Memory)
Socket 1207 – 1207-pin organic land grid array (LGA) packaging
90-nm (0.09-micron) manufacturing process with dual stress liner (DSL) strained silicon-on-insulator (SOI)
227 million transistors
235mm2 die size
1.35-1.40V nominal voltage
125W Max thermal power
55-63 degrees Celsius max ambient case temp for FX-70 and FX-72, 56 degrees for FX-74
FX-70: $599 per pair
FX-72: $799 per pair
FX-74: $999 per pair
Like the Athlon 64 X2 CPUs, the Athlon 64 FX-70, FX-72, and FX-74 support conventional unbuffered non-ECC memory. This means you can use the same off-the-shelf DDR2-800 or DDR2-667 memory used previously on your AM2 setup on the new 4x4 CPUs. Everywhere else though the new FX CPUs more closely resemble AMD’s Opteron CPUs.
For instance, each FX CPU has its own dedicated dual-channel memory interface, with two DIMM slots associated with each processor, just like Opteron. This gives 4x4 twice the memory bandwidth of its predecessor, the FX-62: 12.8GB/sec peak memory bandwidth on an AM2 system versus 25.6GB/sec for 4x4. As a result, total system bandwidth goes from 20.8GB/sec on AM2 to 33.6GB/sec for 4x4.
Keep in mind though that in order to take advantage of this, you’ll need to populate all four DIMM slots with memory. Also like Opteron, 4x4 systems also follow a non-uniform memory access model (NUMA), so you’ll need a NUMA-aware OS such as newer Linux builds, Windows Server 2003 64-bit Edition, or Windows Vista.
Because we’re testing with the GeForce 8800 GTX in this article and don’t have Vista drivers for this GPU, we conducted our tests under Windows XP Pro. We’ve been told by AMD that even though this isn’t a NUMA-aware OS, it shouldn’t affect our benchmark results. Only memory-sensitive applications such as SiSoft Sandra’s memory tests and other memory benchmarks are affected by this.
The other key difference between the new FX CPUs and their predecessors is AMD’s new 1207-pin socket, frequently referred to in the past as Socket F. This is the same socket AMD uses on newer Opteron processors, and as you can see in the photos, the pins are located on the motherboard itself, rather than the underside of the processor.
With 1207 pins on the new socket, frankly we’re glad to see that AMD has moved the pins from the CPU to the motherboard – could you imagine trying to fix a bent pin on your $600 or $1,000 CPU?