AMD CPU shoot-out: Phenom X3 and X4

The birth of AMD’s quad-core Phenom processor was plagued withproblems. After a gestation period more akin to an elephant than a CPU,the new silicon popped out puking and bawling but was clearly a bit ofa runt.
The problem was the now-infamous TLB error that crippled performanceand reduced clock speed with the result that the B2 stepping of Phenomwas only available in two models.

AMD's Phenoms: (clockwise from top left) 9600, X3 8750, X4 9750, X4 9850

Neither the 2.2GHz Phenom 9500 nor the 2.3GHz 9600 delivered enoughperformance to trouble Intel's Core 2 Quad Q6600, which was a directcompetitor at the same price. As an added kick in the teeth, Phenomwould barely overclock while the Intel processor could manage a clockspeed of 3GHz without breaking a sweat.
AMD fixed the TLB problem with its B3 stepping and also got a bitcreative with the model codes that it used. Phenom X4 9x50 denotes aquad-core B3 that effectively replaces the original Phenom. The PhenomX3 8x50 is also a B3 but is unusual in that it's a tri-core processor.Phenom is similar to Core 2 Quad in many respects but there is onesignificant difference as Phenom is a native quad-core design with allfour cores on the same die. By contrast Core 2 Quad is a dual-coredesign, so Intel uses two processor dice to cobble together itsfour-core CPUs.
Naturally, AMD touts this difference as a major advantage for Phenomas it allows HyperTransport to strut its stuff, while Core 2 istheoretically crippled by a lousy communication path through thefrontside bus and then off to the northbridge of the chipset to thememory controller.

It was time for the Phenom X4 9850, and we weren’t surprised to seethat performance was a distinct improvement on the X3 8750 in everyrespect with the exception of pure graphics tests that only stress thegraphics card. The X4 draws 40W more than the X3 which makes it fairlyeasy to deduce how much power each core in a Phenom requires. Thequad-core overclocked slightly better than the tri-core but neither wasimpressive in that department.
The thing that caused us some surprise, however, is the similarityin price. You only pay £10 more for the X4 so why on Earth would youchoose the X3?

Finally, we come to the Phenom X4 9850, which only runs 100MHzfaster than the X4 9750 - 2.5GHz - but there are a couple of otherchanges. The X4 9750 has a TDP of 95W and HyperTransport speed of1.8GHz while the X4 9850 has a TDP of 125W and a HyperTransport speedof 2GHz which rather suggests that the X4 9850 is buzzing along at thelimits of the B3 architecture.
We had heard great things of the X4 9850, with at least one reviewerclaiming a clock speed of more than 3GHz. However, we had nothing likethat degree of success. With the 200MHz clock raised to 225MHz weimmediately suffered a blue screen after Windows had loaded, and thatwas with a clock speed just over 2.8GHz.
The system was pretty much OK with a clock speed of 220MHz (2.75GHzCPU speed) although 3DMark Vantage refused to run however the X4 9850required more cooling than the other Phenoms. Indeed we had to removethe add-in fan controller from the CPU cooler to get the fan speed highenough to cool the CPU properly.

That’s all well and good but just take a look at our test resultsfor Core 2 Quad Q6600. On its stock speed of 2.4GHz it wiped the floorwith Phenom and when we overclocked it to 3.0GHz it made the AMDsilicon look rather limp.
VerdictThe B3 stepping of Phenom is a distinct improvement over theoriginal B2 but that’s not saying much. Intel has cut the price of Core2 to such an extent that there is no compelling reason to buy a Phenombeyond the fact that you might not like Intel very much. Fair enough,we'd say, but for everyone else, Intel has grabbed the initiative. Overto you, AMD.

If I were AMD I'd drop the whole Phenom idea. It became a complete failure IMO and its the only thing that gave Intel bragging rights. I'd like to hear about the quad core Opterons, I'm a bit excited about those, I feel they can make a difference. AMD ought to take the easy way out like Intel until they can develop a true quad core like the Phenom except actually successful. When it comes to dual cores, I'm supporting AMD but if I ever get a quad core (which is unlikely) I'm going with the either Intel or Sun. Its a shame ATI is holding back AMD's funds, it must be hard for them to catch up on multiple projects.