Summary: With Athlon 64 FX-70 CPUs starting at $305, AMD's Quad FX platform is the cheapest way to get into quad-core gaming. In this article we take a look at the overclocking potential of the FX-70, comparing its performance to a slew of other quad-core CPUs that are competing for your hard-earned dollars. How does the FX-70 stack up to the others when overclocked? Find out in this article!
Quad-core gaming: it’s coming
The quad-core gaming era is about to begin. In less than a week, the world’s first quad-core enabled game will hit store shelves, Gas Powered Games/THQ’s highly anticipated 3D RTS, Supreme Commander.
AMD’s FX-70: Cheapest quad-core available
As we just mentioned, the Athlon 64 FX-70 shares all the key specs found in the rest of the Quad FX platform yet it costs significantly less.
If you recall, the Quad FX processors are based around AMD’s new 1207-pin socket dubbed Socket F (ASUS refers to it as Socket L1). With the debut of the new socket, AMD now uses organic land-grid array packaging and the pins are now located on the motherboard itself rather than the underside of the processor. This makes processor installation a lot easier, as you no longer have to worry about bent pins on the processor.
Fundamentally the new Quad FX processors are based on AMD’s Opteron architecture. Like AMD’s Opteron processors, each FX CPU has its own dedicated dual-channel memory interface, with two DIMM slots associated with each processor. This gives the quad FX platform twice the memory bandwidth of AMD’s AM2 platform, 12.8GB/sec peak memory bandwidth on an AM2 Athlon 64 FX-62 system versus 25.6GB/sec for FX-70. As a result, total system bandwidth goes from 20.8GB/sec on AM2 to 33.6GB/sec for a quad FX processor like the FX-70.
Of course, here we should remind you that in order to take advantage of this, you’ll need to populate all four DIMM slots with memory, otherwise the system will run in single-channel memory mode, resulting in slower performance. 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.
One key difference between the latest FX processors and Opteron however is that the FX CPUs support conventional, unbuffered, non-ECC memory. This means you can use the same off-the-shelf DDR2-800 or DDR2-667 memory already used for AM2 on the new FX CPUs.
This table sums up the Quad FX CPU lineup as it stands now:
Taking the FX-70 beyond 2.6GHz
Despite the efforts of a handful of other manufacturers, dual CPU overclocking has never truly taken off in the mainstream segment. Arguably the best attempt came from Abit way back in 1999 with their BP6 motherboard. One popular solution was to overclock two Celeron 366 processors to 550MHz, giving end users high-end performance at a fraction of the cost of using dual Pentium III or Xeon processors, but dual CPU overclocking on the AMD platform hasn’t been truly viable for one reason or another up until now.
Keep in mind that the L1N64-SLI WS is an extended ATX form factor motherboard, so you’ll need a large case in order to house it.
In order to keep the FX-70 processors as cool as possible for our overclocking endeavors, we decided to skip the stock AMD heatsink/fan units, opting instead to use a pair of Zalman CNPS9700 coolers. At stock speeds, we noted idle temps that were about 10 degrees Celsius cooler as a result of using the Zalman coolers, with the processor running around 31-35 degrees Celsius.
The CNPS9700s aren’t officially on the list of approved Socket F coolers, but they mounted on the board just fine, although it was a very tight fit. In hindsight the CNPS 9500 is a little smaller and probably would have been easier to install because of this, but oh well, we were happy with our OC’ing results:
We were able to overclock the FX-70’s to 3.12GHz (15.0x208). In order to get there we had to use the vcore over-voltage setting, which was set at the max setting of 200mV. We were actually able to boot up to much higher speeds, the CPU ran up to 3.2GHz with no problems. At that speed the system would boot as far as the Windows XP splash screen; at that point, the system wouldn’t lock up, but it wouldn’t boot into Windows either. It literally just sat there as if it wasn’t sure if it wanted to boot or not, with the HDD occasionally being accessed.
Because of this, we think we could have pushed the CPU further with a little more voltage. In fact, ASUS’ initial BIOS provided more CPU voltage options and we’ve asked ASUS if perhaps they’ll reconsider and integrate more voltage settings for the CPU. We’ll be keeping an eye on this to see if anything develops.
So how does the FX-70 perform in comparison to the other quad-core CPUs at 3.19GHz? Let’s find out!
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Company of Heroes
The FX-70 really shines though when it’s overclocked. We pushed our FX-70s to 3.12GHz and feel that we probably could have gone a little further if we’d had a little more voltage. At 3.12GHz though the FX-70 really impressed us, outperforming both the FX-74 and Intel’s Core 2 Quad Q6600 in some cases, both of which cost significantly more than the FX-70.
The only real downside to the Quad FX platform is the dearth of motherboards available at the moment. The ASUS L1N64-SLI WS is the only compatible motherboard right now. The L1N64-SLI WS is a great board and it’s decked out with features, but we can’t help but feel that if more motherboards were available on the market, prices would be a little lower. This in turn would make the Quad FX platform more affordable for enthusiasts on a budget who would like to get their feet wet with quad-core without breaking the bank.
For FiringSquad readers in this situation, fortunately we can report that the incremental upgrade path is a very viable option: simply buy one FX-70 processor now along with the L1N64-SLI WS motherboard and memory, and buy the second FX-70 CPU six months from now when you’ve got more money to splurge on an upgrade. By then CPU prices will be cheaper as well. The L1N64-SLI WS platform runs just fine with one FX-70 installed, the system BIOS and OS treats it just like a normal dual-core CPU.
Officially AMD would probably discourage end users from going this route, but in our opinion, it’s a very solid option for enthusiasts on a budget. It actually makes a lot of sense considering the lack of quad-core games out there today.
It’s surprising that AMD doesn’t promote this upgrade path more openly, as they’ve clearly got the least expensive quad-core solution by far with the FX-70. And by going the incremental upgrade route, the Quad FX platform is even more tempting.
Now all we’re waiting for is the quad-core games to ship. Fortunately we won’t have to wait too much longer for that to happen. Once that occurs, we can finally benchmark AMD’s Quad FX platform against Core 2 Quad and all the speculation on the two platforms and how they perform in games can finally be put to rest…
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