Phenom II X4 965 slips into more modest thermal envelope

Some folks scoffed when AMD elected to introduce the Phenom II X4 965 processor back in August with a 140W thermal design power (TDP), because that pushed beyond AMD’s customary peak of 125W for desktop processors. The move wasn’t without precedent, but it signaled that AMD’s 45nm chips couldn’t reach the 3.4GHz mark without a bit of extra juice.

Now, some months later, AMD has introduced a revised version of the Phenom II X4 965 Black Edition processor (say the name in a single breath for extra credit, kids) with a 125W TDP. The thermal improvement comes hand in hand with a couple other tweaks. For one, the memory controller has been altered to support the use of four DDR3 DIMMs at 1333MHz.

Also, an enhanced halt state, C1E, is now supported in hardware. Naturally, implementing power-state switching in hardware is much faster than software, and AMD says that means power management schemes should now have “virtually no impact” on performance. AMD processors have had a bit of a rocky history on this front in recent years, with power-management features potentially compromising performance in certain situations. Sounds like they’re cleaning that up. Still, I wouldn’t expect much of a difference in regular use. We tested with power management schemes enabled in our last major CPU review, of the Intel Lynnfield processors, and we did some spot checks along the way with power management disabled, too. Generally, we found that enabling and disabling power management had very little to no effect on most tests.

The reduction in the processor’s TDP rating comes with a real reduction in power use. Here’s a quick glance at power use from the Damage Labs test bench.  These results show full-system power draw following the test methods and configurations outlined in our Lynnfield review.

There’s virtually no change to power draw at idle, but power draw under load is down by 9W versus our example of the earlier 140W version of the X4 965. That’s good, but then in this particular application, the X4 965’s performance just barely surpasses that of the Core i5-750. So the power efficiency picture isn’t altered much. Here’s the proof.

Still, moving into the 125W thermal envelope ought to allow the X4 965 to find its way into more systems from big PC makers, along with enabling broader compatibility with existing AMD-oriented mobos and CPU coolers.