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 |
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hyc - Monday, February 9, 2009 - link
I was looking for the test that justified the "DDR3 not worth it" conclusion, but didn't see it.Where did you show the results of testing the X4 910 against the X4 940, with CPU and NB clocks set identically? If you didn't test this, then how can you make any conclusion about DDR2 vs DDR3 performance on Phenom II? If I missed it, sorry for being blind.
7Enigma - Monday, February 9, 2009 - link
I'm hoping since this just went up they forgot to include a couple pages. If not, hopefully they are retesting ASAP to include data....jchan2 - Monday, February 9, 2009 - link
i'm intersted in seeing the benchmarks myself.if it's true that DDR2 vs DDR3 doesn't make much difference in performance, then what's the purpose of getting DD3?
TheFace - Monday, February 9, 2009 - link
So that when the prices DO drop later this year, they aren't caught with their pants down playing catch up on the memory compatibility front. Also, when Joe Schmoe runs to Worst Buy to replace the computer that he got 5 years ago, with a new $600 model, he can look on the box and see DDR3 which MUST be faster than DDR2.It's a selling point. In retail, ANYTHING is a selling point as long as there is a disparity in knowledge held by the parties involved.
Targon - Monday, February 9, 2009 - link
Compatibility. When Intel made the jump to DDR2, AMD waited until the prices came down on the memory. If there is no performance advantage, then the only reason to change memory types is for price reasons.For large OEMs like Dell, HP, and Gateway, it is more cost effective if all systems use the same type of memory. At this point though, since there is a price premium for DDR3 memory, just having DDR3 support on the CPU would not make an OEM add more AMD based machines to their list of systems sold.
Gary Key - Monday, February 9, 2009 - link
We are still working on the comparison, but all of the initial numbers pointed to a tie between DDR3 and DDR2 in our results so far. The BIOS releases for the AM3 boards are just now coming up to speed. I had planned on significantly more information in the overclocking section but we just received a new BIOS for the 790FX boards that allow DDR3 clocking above 1600 or so.However, at like core clock speeds, DDR2-1175 C5 is just as fast as DDR3-1600 C7 in most of the benchmarks at this point. We are running tests now at the lower end of the spectrum to show 800/1066 DDR2 vs 1066/1333 DDR3. Those results still show little if any differences.
thepiratebay - Wednesday, February 25, 2009 - link
Intel Core i7 920 Nehalem 2.66GHzin ur upper test as u can seee 2.8?????
Enoc - Tuesday, February 10, 2009 - link
DDR3 is not the problem, Deneb is bottlenecked on NB-L3 side... what it needs is NB at 2,800mhz+ with DDR3 1,600mhz+ for a good scaling...Denithor - Monday, February 9, 2009 - link
"We are still working on the comparison"SO - why would you even reference DDR3 as being useless in your title if you aren't going to provide evidence to back up this comment?
Gary Key - Monday, February 9, 2009 - link
We are still working on it but all results so far point to that being the case right now. It is difficult to have meaningful results ready when receiving BIOS releases that actually stabilize a board just a few hours before going to print. ;)