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Phenom II X4 810 and X3 720 Processor Review - DDR3 Arrives for AMD

Author: Josh Walrath
Subject: Processors
Manufacturer: AMD

The New Kids

    The X3 720 BE is the part that AMD is very excited about, as they feel it will be quite popular with the budget enthusiasts.  Since it is a Black Edition, it features an unlocked multiplier.  Though it is built off the same 45 nm die as the X4 940, but with one core is disabled.  This potentially means that because it draws less power overall than the fully functional chips, it could overclock higher.  The price is also very competitive, and in 1K trays AMD is suggesting a very reasonable $145 US.  This is a 95 watt TDP part, which is obviously a bit lower than the 125 watt spec’d X4 940 and 920 parts.

    The X3 720 runs at 2.8 GHz and features the full 6 MB of L3 cache, which bodes well for the efficiency of this processor.  The Phenom architecture seems to enjoy having a large amount of L3 cache per core, and when reducing the package to three cores, that means there is more L3 cache available on a per-core basis.  Each individual core still features 64 KB of i-cache, 64 KB of d-cache (both considered L1 cache), and 512 KB of L2 cache.


My particular sample runs at 1.325 volts at stock.  I am frankly a bit surprised by how high of voltage the Phenom II parts run at.  The Phenom II X4 940 hits 1.35 volts, which is the same applied to the Phenom 9950.

    The only other major change is that the north bridge portion of the chip (the “un-core”) now runs at 2 GHz vs. the 1.8 GHz that the AM2+ compatible X4 940 runs at.  This should speed up memory performance, as well as allow faster access to the L3 cache (plus slightly lower latencies).  All of this makes the X3 look to be a bit more efficient and have a slightly higher IPC per core.

    The X4 810 is a slightly different beast than the previous products.  This chip runs at 2.6 GHz with a 2 GHz un-core, but the L3 cache is cut down from 6MB to 4MB.  The reduction of clockspeed and cache size allows AMD to rate it at 95 watts TDP.  This product is aimed squarely at the Intel Q8200, and AMD feels that it should outperform that part at stock speeds.  Pricing for the X4 810 in 1K trays is $175 per chip.  The X4 810 does not have its multiplier unlocked, so increasing the bus speed is the only good way to OC it.  Lowering the HTT multiplier should allow HTT speeds to hit upwards of 250 MHz or more, which would allow this processor to hit speeds of 3.2 GHz+.  This part is, oddly enough, priced directly next to the older Phenom 9950, and it should outperform that older part by a fair margin (5% to 10% in most instances).

The X4 810 runs at a slightly lower 1.3 volts.  This is a bit more in line with what I would expect, but AMD certainly has room for improvement.

    While at first glance this looks as if AMD is cannibalizing their Phenom 9950/9850 sales, this is in fact not true.  With the introduction of the X4 940 and 920 parts, users who were interested in the older Phenoms suddenly had a big reason why not to buy them anymore.  Also, AMD is aggressively shutting down 65 nm production, and as of the end of last month their production was supposed to be at around 50% for 45 nm.  By the end of February, 45 nm production should be well above what AMD is putting out at 65 nm (I would guess a 60/40 split).

Which one is which?  How fast can you count 938 and 940 pins?  For those who are not willing to, the AM3 chip is on the left.  This is in direct contrast with the Intel 775 LGA processor at the top.

    These processors, as mentioned before, are AM3 parts.  The AM3 specification is compatible with DDR-3 and DDR-2 memories, runs the HyperTransport connection at up to 5600 MT/s (though both run at 4000 MT/sec), and will fit in both AM3 and AM2+ sockets.  Physically the chips have 938 pins, which is two less than the AM2/2+ sockets (940 pins).  This allows AM3 parts to fit in both AM2+ and AM3 sockets, but without a hammer and some force the AM2+ chips will not fit in AM3 sockets.