AMD Phenom X4 9850 Black Edition

Verdict: [+] BlackTLB bug fixed; fastest Phenom yet; unlocked multiplier
[-]GreyDoesn't like extra voltage; poor overclocker; poor performance; Q6600 is cheaper

The Phenom X4 9850 is what AMD's Phenom should have been when it first launched in December 2007. The new 'X4' suffix fits in with AMD's Athlon 64 X2 and Radeon HD 3870 X2 branding, and makes it obvious that the Phenom X4 9850 is a quad-core CPU. More importantly, this Phenom doesn't suffer from the Translation Lookaside Buffer (TLB) errata that limited performance and overclocking. Fixes aside, the big question Phenom must answer is whether or not, in its new B3 stepping guise, it can match a comparably priced Intel Core 2 Quad for speed.We'll start with the good news. The X4 9850, the top-of-the-range Phenom, clocked at 2.5GHz, is only £7.12 more expensive than the Core 2 Quad Q6600. Priced at just £110.32 the 2.2GHz Phenom X4 9550 is the cheapest quad-core processor on the market. Oddly, the 2.4GHz Phenom X4 9750 is, at time of writing, £134.88, making it more expensive than the faster (and multiplier-unlocked) Phenom X4 9850.
However, bagging a Q6600 for only £124.42 is tempting unless you have a Socket AM2+ motherboard. A Phenom will work in older Socket AM2 boards, but check that your VRMs can handle the new processor and that the manufacturer of your motherboard has released a Phenom-supporting BIOS update.PERFORMANCE
Sadly, the benchmarks of the X4 9850 speak for themselves (click the Benchmarks tab, above). At stock speeds, the Q6600 is faster than the X4 9850. It's 10 per cent faster in Cinebench R10, 44 per cent faster in SuperPi 1M and 14 per cent faster overall in our Media Benchmarks. Clearly, the Phenom needs to offer better performance, so we tweaked the BIOS of our Gigabyte GA-MA790FX-DQ6 test motherboard (ignoring the Windows-based Overdrive overclocking tool for everything but temperature monitoring). This CPU's Black Edition label signifies that it's multiplier unlocked, so we easily found its maximum frequency by increasing the multiplier. The chip maxed out at 3GHz with a 15x multiplier.Finding a processor's maximum frequency involves overvolting it, but even with a modest vcore of 1.45V - only a 0.2V overvolt - the Phenom threw out more heat than a randy mare in the breeding season. Overvolted, Overdrive reported the CPU temperature as 93°C, even with a handful of fans blowing on the test rig.With a vcore lower than 1.45V, the Phenom couldn't manage a 3GHz clock speed. Trying to tweak the HTT and use a lower multiplier to nudge the Phenom beyond the 3GHz barrier resulted in BSODs, lock-ups and failed POSTs. We finally left the HTT at 200MHz and used the 15x multiplier to obtain a 3GHz Phenom.OVERCLOCKED PERFORMANCE
While the overclock brought a burst of extra speed, a 3GHz Phenom can't match the 3.6GHz to which a Core 2 Quad Q6600 will typically overclock with air cooling. The benchmark scores are a nightmare for AMD. The overclocked Q6600 is 72 per cent quicker in our multitasking test than with the overclocked X4 9850, and the Handbrake video encoding test ran 31 per cent faster with the 3.6GHz Q6600 than with the 3GHz X4 9850.More worrying for AMD is that you may already have achieved the performance of a Phenom from your Athlon 64 X2. As the graphs show, the 3.4GHz dual-core Athlon 64 X2 6400+ more than holds its own against the new top-end quad-core Phenom. If you overclocked your Athlon 64 X2 to 3.4GHz, you may not even notice the difference between using that chip, and upgrading to the Phenom X4 9850. You can see how your system compares by downloading the Custom PC benchmarks.CONCLUSIONThis B3 stepping of the Phenom CPU is an improvement over the initial Phenoms. It solves the TLB errata and overclocks a little better - we pushed our test chip to 3GHz using air cooling. However, the Intel Core 2 Quad Q6600 is faster, more overclockable and creates less heat. Intel's price cuts make its case even more watertight. AMD will need faster, cooler Phenoms if it's to seriously challenge Intel.You can buy the AMD Phenom X4 9850 Black Edition from Scan here
For more information on the AMD Phenom X4 9850 Black Edition, see AMD's website