Socket AM3, Phenom II and DDR3: AMD's new CPU platform reviewed
What advantages are delivered by AMD's AM3? PC Games Hardware tests the new CPU platform, including DDR 3 RAM.
AM3: Phenom II X4 with DDR3 RAM
In late April not only the new Phenom II X4 955 BE, but also the socket AM3 have officially been released. In combination with the Radeon HD 4890/1G, which has been available for some time already, and the free tool Overdrive those components represent a "Refresh” of AMD's Dragon platform.
Although AM3 CPUs hit the market in February, AMD didn't advertise the new socket and always recommended to run tests with AM2+ boards. But this has changed when the Phenom II X4 945 and X4 955 BE were introduced: Now the AM3 is the new reference platform for AMD processors. All future Phenom II CPUS will possibly be AM3, so the X4 945 and X4 940 BE might be the only 45 nanometer Phenoms that support the socket AM2+ only.
But what changes with the new socket at all? Not many things. New processor coolers for example are not required; AM3 delivers only one important change: support of DDR3 memory. AM2+ boards support DDR2 only and Intel already switched to DDR3 with the Core i7. But DDR§ RAM is still more expensive than the older standard - the same applies to the first AM3 boards. Is the technology worth the money? Or should a new AM3 CPU be run on a AM2+ board with DDR2, a combination that still is possible? We tested it.
AM3: CPU overview
All quad-core AM3 CPUs up to the Phenom II X4 955 BE are based on the 45 nanometer Deneb design. The L2 cache is 512 KiByte per core big and the L3 cache is up to 6 MiByte big. The only differences between the AM3 and AM2 processors are two missing pins and a Hypertransport link that has been accelerated from 1,800 to 2,000 MHz. But while AM3 CPUs are downwards compatible, it is not possible to run an AM2 CPU on an AM3 board.
|Processor||Code name||Cores||Frequency||Multipl.||HT-frequency||L2 Cache||L3 Cache||Socket||RAM-Contr.|
|Phenom II X4 955 Black Edition||Deneb||4||3.2 GHz||16 (open)||2,000 MHz||2 MiByte||6 MiByte||AM2+/AM3||DDR2/DDR3|
|Phenom II X4 945||Deneb||4||3.0 GHz||15||2,000 MHz||2 MiByte||6 MiByte||AM2+/AM3||DDR2/DDR3|
|Phenom II X4 940 Black Edition||Deneb||4||3.0 GHz||15 (open)||1,800 MHz||2 MiByte||6 MiByte||AM2+||DDR2|
|Phenom II X4 920||Deneb||4||2.8 GHz||14||1,800 MHz||2 MiByte||6 MiByte||AM2+||DDR2|
|Phenom II X4 910||Deneb||4||2.6 GHz||13||2,000 MHz||2 MiByte||6 MiByte||AM2+/AM3||DDR2/DDR3|
|Phenom II X4 810||Deneb||4||2.6 GHz||13||2,000 MHz||2 MiByte||4 MiByte||AM2+/AM3||DDR2/DDR3|
|Phenom II X4 805||Deneb||4||2.5 GHz||12. Mai||2,000 MHz||2 MiByte||4 MiByte||AM2+/AM3||DDR2/DDR3|
|Phenom II X3 720 Black Edition||Heka||3||2.8 GHz||14 (open)||2,000 MHz||1.5 MiByte||6 MiByte||AM2+/AM3||DDR2/DDR3|
|Phenom II X3 710||Heka||3||2.6 GHz||13||2,000 MHz||1.5 MiByte||6 MiByte||AM2+/AM3||DDR2/DDR3|
AM3: DDR3 RAM tested
Officially the integrated memory controller of the Phenom II supports DDR3-1333 "only”. Unofficially more is possible of course, but during our tests only one memory kit was running stable at DDR3-1600: the OCZ Platinum OCZ3P18004GK. We estimate that most memory kits are still optimized for Intel's Core i7 and that OC-Kits for AM3 systems will follow soon.
An increased frequency is always linked to higher latencies. But how is the performance affected? In the synthetic memory benchmark Sisoft Sandra 2009 DDR3-1600 on the Phenom II X4 955 BE taking the lead, but DDR2-1066 with sharp latencies of 5-5-5-18 can almost keep the pace. In the game tests the results vary as the benchmarks below reveal: Left 4 Dead (dt.) obviously favors low latencies; higher frequencies don't deliver big differences. For all the other benchmarks we stuck to the two fastest modes: DDR2-1066/5-5-5-18 and DDR3-1600/7-7-7-21.
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