The Phenom II X4 810 & X3 720: AMD Gets DDR3 But Doesn't Need It
by Anand Lal Shimpi on February 9, 2009 12:00 AM EST- Posted in
- CPUs
Lower TDPs, Faster un-core, DDR3 Support: The new Phenom II
All of the CPUs launching today are Socket-AM3 compatible. If you remember from my original Phenom II article, a Socket-AM3 CPU can work in both AM3 and AM2+ motherboards. I made a cute little compatibility matrix for you guys:
| CPU/Motherboard | Socket-AM2 MB | Socket-AM2+ MB | Socket-AM3 MB |
| Socket-AM2 CPU | Yes | Yes | No |
| Socket-AM2+ CPU | Maybe | Yes | No |
| Socket-AM3 CPU | Maybe | Yes | Yes |
AMD carefully engineered its AM3 memory controller allowing it to operate in both DDR2 and DDR3 modes. Any AM3 CPU can thus work in either a Socket-AM3 motherboard with DDR3 memory, or in a Socket-AM2+ motherboard with DDR2 memory. Backwards compatibility with original Socket-AM2 motherboards is up to the motherboard vendor, AMD does not validate any AM3 CPUs in regular AM2 motherboards.
The new Socket-AM3. Socket-AM2/AM2+ CPUs won't fit in here. But AM3 CPUs will fit in AM2+ boards.
All of the Socket-AM3 Phenom II CPUs are 95W TDP parts, compared to 125W for the first two chips that launched in January. The other notable change is that all of the AM3 CPUs run their un-core (North Bridge + L3 cache) at 2.0GHz instead of 1.8GHz like the AM2+ Phenom II processors.
Socket-AM3 Motherboards: Don't Bother Yet
I've had a Socket-AM3 motherboard here for a while but honestly the performance just isn't worth it. While it's taken a while to get stability up to par with AM2+, overall system performance remains unaffected. The Socket-AM2+ to Socket-AM3 transition looks a lot like the Socket-939 to Socket-AM2 transition we saw back in 2006.
A Socket-AM3 CPU (left) vs. a Socket-AM2 CPU (right) Note the missing pins on the AM3 chip.
Thankfully AMD gives you the option to ugprade whenever you'd like. You can buy a Socket-AM3 CPU today and use it in either an AM2+ board or an AM3 board, provided there's proper BIOS support. DDR3 memory is still more expensive than DDR2 and offers no real world performance advantage even at DDR3-1333 speeds.
Note that Socket-AM3 CPUs will only officially support one DIMM per channel running at 1333MHz. You'll need to run at 1066MHz speeds if you're running four DIMMs. When DDR2 and DDR3 memory reach price parity at the end of this year, AMD will be in a good position to make the transition. But if you're buying today, find a good AM2+ board and some cheap DDR2 memory.
The Test
| Motherboard: | Intel DX58SO (Intel X58) Intel DX48BT2 (Intel X48) MSI DKA790GX Platinum (AMD 790GX) |
| Chipset: | Intel X48 Intel X58 AMD 790GX |
| Chipset Drivers: | Intel 9.1.1.1010 (Intel) AMD Catalyst 8.12 |
| Hard Disk: | Intel X25-M SSD (80GB) |
| Memory: | G.Skill DDR2-800 2 x 2GB (4-4-4-12) G.Skill DDR2-1066 2 x 2GB (5-5-5-15) Qimonda DDR3-1066 4 x 1GB (7-7-7-20) |
| Video Card: | eVGA GeForce GTX 280 |
| Video Drivers: | NVIDIA ForceWare 180.43 (Vista64) NVIDIA ForceWare 178.24 (Vista32) |
| Desktop Resolution: | 1920 x 1200 |
| OS: | Windows Vista Ultimate 32-bit (for SYSMark) Windows Vista Ultimate 64-bit |
Facebook
Twitter
RSS
77 Comments
View All Comments
just4U - Monday, February 9, 2009 - link
I think you were a bit optimistic in your prediction that DDR3 will be at price parity with DDR2 by years end but otherwise a good review.I do have a question tho as I am not 100% sure on it. The cpu's that were launched in January (920/40). Are they also compatable with DDR3 boards? Or just these new cpu's?
faxon - Friday, May 1, 2009 - link
really? because right now newegg is selling a 2x2GB kit of Gskill cas9 1600 for $59, and the like kit of DDR2 cas5 is only $56. all we need now is for latency on the ram to drop at the same low voltages seen on i7 kits and i would call that price parity, not that you will even really notice the latency difference except in synthetic benchmarks anymoreDrMrLordX - Monday, February 9, 2009 - link
To the best of my knowledge, AM2 and AM2+ Phenom/Phenom IIs will not support DDR3. Their memory controllers just can't hack it.hyc - Monday, February 9, 2009 - link
How so? Barcelona/Phenom-I already had the dual memory controllers, they were just never enabled on any motherboards.Targon - Monday, February 9, 2009 - link
For DDR3 support you need a DDR3 supporting CPU. From the sound of it, the processors are the socket AM3 type, meaning they will work in both socket AM2+ and socket AM3 motherboards. If a processor is for socket AM2/AM2+, it will NOT work in a DDR3 motherboard.The way it works is simple, the DDR3 versions of the processor have both DDR2 and DDR3 memory controllers, so will work with either type of memory. The DDR2 processors(X4 940 and 920) only have a DDR2 memory controller(it is dual channel, but that isn't the same as supporting both memory types), so will only work in a socket AM2 or AM2+ motherboard.
The X4 945 and 925(I think) will be the DDR3 supporting versions of the current chips.
Again, you can NOT put a socket AM2+ chip in a DDR3 board, it won't work(pin is blocked in the socket to avoid frying the chip). Even if you could put the chip in a DDR3 board, without the DDR3 memory controller on the CPU, it just would not work.
grb1212 - Tuesday, March 16, 2010 - link
your not totally right if u have a am2/am2+/am3 compatible board and it uses ddr3 if u use a ddr2 compatible processor ddr3 will work with a ddr2 processor but it will act like ddr2 memory as far ass performanceTheFace - Monday, February 9, 2009 - link
This may help.http://www.tomshardware.com/reviews/socket-am3-phe...">http://www.tomshardware.com/reviews/socket-am3-phe...
The chips released today seem to be the only ones that work in AM3. But the chips released today will also work in AM2/AM2+. It's just, as has been stated repeatedly, the chips designed for AM2/AM2+ won't work in AM3.