AMD Socket-AM2: Same Performance, Faster Memory, Lower Power
by Anand Lal Shimpi on May 23, 2006 12:14 PM EST- Posted in
- CPUs
AM2 in Detail
Of course the most prominent feature of AMD's Socket-AM2 platform is the new socket and its support for DDR2 memory. As we've already mentioned, Socket-AM2 is a 940-pin socket that is keyed differently from the original 940-pin Athlon 64/Opteron sockets; only AM2 processors will physically fit into an AM2 motherboard.
Socket-939 (left) vs. Socket-AM2 (right)
Socket-939 |
Socket-AM2 |
 |
 |
One of the Athlon 64's strongest selling points continues to be its on-die memory controller, which has of course been significantly changed for the new Socket-AM2 platform. All AM2 CPUs feature a 128-bit wide DDR2 memory controller, compared to the 128-bit DDR memory controller that we've come to know from the Socket-939 platform. A DDR2 memory interface actually requires more pins than a DDR1 interface, but AMD was able to keep the AM2 pin count down by removing a large number of unnecessary pins on the Athlon 64's package. When the Socket-940/939 Athlon 64s were first designed, approximately 10% of their pins were redundant and could be removed in later designs. Not desiring to introduce a new socket as frequently as its competition had, AMD waited until Socket-AM2 to remove those unnecessary pins thus enabling a dual-channel DDR2 interface in virtually the same pin count as the earlier DDR1 equipped CPUs.
All of the Socket-AM2 CPUs support up to DDR2-667, but the AM2 Athlon 64 X2 and Athlon 64 FX models support up to DDR2-800. Since Socket-AM2 unifies AMD's desktop socket strategy, all Semprons, Athlon 64s, X2s and FX processors will feature this dual channel DDR2 memory controller.
Corsair partnered with AMD and NVIDIA for the Socket-AM2 and nForce 500 review kits
The lineup of Socket-AM2 processors being introduced today are in the table below:
| CPU | Clock Speed | L2 Cache Size | TDP | Price |
| AMD Athlon 64 FX-62 | 2.8GHz | 1MBx2 | 125W | $1031 |
| AMD Athlon 64 X2 5000+ | 2.6GHz | 512KBx2 | 89W | $696 |
| AMD Athlon 64 X2 4800+ | 2.4GHz | 1MBx2 | 89W | $645 |
| AMD Athlon 64 X2 4600+ | 2.4GHz | 512KBx2 | 89W | $558 |
| AMD Athlon 64 X2 4400+ | 2.2GHz | 1MBx2 | 89W | $470 |
| AMD Athlon 64 X2 4200+ | 2.2GHz | 512KBx2 | 89W | $365 |
| AMD Athlon 64 X2 4000+ | 2.0GHz | 1MBx2 | 89W | $328 |
| AMD Athlon 64 X2 3800+ | 2.0GHz | 512KBx2 | 89W | $303 |
| AMD Athlon 64 3800+ | 2.4GHz | 512KB | 62W | $290 |
| AMD Athlon 64 3500+ | 2.2GHz | 512KB | 62W | $189 |
| AMD Sempron 3600+ | 2.0GHz | 256KB | 62W | $123 |
| AMD Sempron 3500+ | 2.0GHz | 128KB | 62W | $109 |
| AMD Sempron 3400+ | 1.8GHz | 256KB | 62W | $97 |
| AMD Sempron 3200+ | 1.8GHz | 128KB | 62W | $87 |
| AMD Sempron 3000+ | 1.6GHz | 256KB | 62W | $77 |
There's basically no price premium for the new Socket-AM2 chips, encouraging a quick transition to AMD's new DDR2 platform.
You will also notice that none of the model numbers have changed, so an Athlon 64 X2 4800+ on Socket-AM2 has the same clock speed and L2 cache size as the Socket-939 version. Since AMD's model numbers haven't changed, you already know not to expect any major changes in performance with Socket-AM2. In fact, the only difference on the CPU side is the introduction of the new Athlon 64 FX-62, Athlon 64 X2 5000+ and Athlon 64 X2 4000+.
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peternelson - Tuesday, May 23, 2006 - link
I see no benchmarking in 64 bit mode.
This is the future, and for maths, Intel's 64 bit was more of a lame copy of AMD 64 bit performance.
In future this will be increasingly important so even if 32 bit performances are comparable, I'd want to make sure the picture is the same running 64 bit apps.
Also you summarise "same performance, faster memory, less power". True, but you FORGET one of the main benefits: Pacifica Virtualisation.
True hardware virtualisation adds to the actual WORK you can keep that processor busy with. It saves time by letting you switch OS instances without rebooting timewasting.
As it is hardware based VT you should even be able to virtualise an UNMODIFIED OS like Win XP, maybe even Vista!
So please play with Xen3.
As you say virtualisation "works" then it is a BIG factor for me in choosing AM2 over 939, (all other things being equal).
Also the fastest 939 chips have been produced, and AM2 is reaching higher models now.
So if you want the VERY fastest, it is only available on AM2.
Don't forget: Not just performance, but performance PER WATT. For these AM2 chips that is similar to 939.
However, the announcement of 65W EE and EVEN 35W SFF EE!!! are significant compared to the standard 89W
Intel seem to be positioning Conroe as being "33% better" on performance per watt. However, Conroe isn't even here but when it is, it may not be able to compete with AMD low power offerings.
Also consider the whole system for conroe vs AMD. Because that AMD power INCLUDES the memory controller, whereas Intel doesn't. The whole motherboard etc may use less power.
Also in terms of entire system cost, motherboards for AM2 appear to be a bit cheaper than their Intel equivalents, which may offset the current high prices of AMD processors.
fitten - Wednesday, May 24, 2006 - link
You should check out the Woodcrest (server targeted Conroe core) previews for power measurements. Performance per Watt, Woodcrest wins (and will be available in 3 weeks)... Absolute power usage under load, Woodcrest wins... and note that the power measurements are for the complete system (video card and HDDs included). (Deep power conservation couldn't be tested on Woodcrest because the parts didn't have it enabled as they were engineering samples.)Also, check out the 64bit vs. 32bit comparisons in programs like Cinebench 9.5. Seems Woodcrest 64bit gives a nice boost there (showing that it isn't just a 'lame copy').
You also seem to forget that Intel already has virtualization extensions out in currently shipping processors (much less Conroe+).
As far as price, there have been price lists published already. High end Conroe parts are already listed for 1/2 the price of the high end AMD parts... at $500 that gives another $500 for purchase of a motherboard before it touches just the CPU cost of the AMD... I doubt that the motherboards will be that expensive.
I have 7 AMD machines (four are Athlon64s or X2s) but right now, it looks like my next machine will be a Core2 one. AMD needs to get an answer out... soon. K8L isn't going to cut it. Sure, it'll be good at FPU but the vast majority of work done by CPUs is integer, which are what the majority of improvements are in Core2 (not that they don't have good FPU improvements). So, if you're in a government lab running FPU intensive simulations, K8L may be for you. If you're anyone else, K8L as it has been described looks kind of anemic and not a match for Core2.
Maybe the real K8L will surprise us, who knows, but it is at least 6 months away (if not longer). By that time, Intel will already be 25% into it's 2-year cycle for the next Core derivative chip (probably farther, time between releases is set to 2-years). AMD looks to be in a bad situation right now... If they have something they're keeping secret, IMO, they need to at least tease us with it. K8L is not a tease, it's only slightly more than a stifled yawn. The longer they go without giving us something to look forward to, the more it looks like they are in major trouble.
Accord99 - Wednesday, May 24, 2006 - link
[quote]Don't forget: Not just performance, but performance PER WATT. For these AM2 chips that is similar to 939.However, the announcement of 65W EE and EVEN 35W SFF EE!!! are significant compared to the standard 89W
Intel seem to be positioning Conroe as being "33% better" on performance per watt. However, Conroe isn't even here but when it is, it may not be able to compete with AMD low power offerings. [/quote]
Given that Woodcrest 3.0GHz has a TDP of 65W, which is borne out by power measurements conducted by Techreport and 2CPU, it's likely that a Conroe that matches the performance of the 35W X2 will at the very least, also match it in power.
soydios - Tuesday, May 23, 2006 - link
AMD motherboards are less expensive because they don't have to put in a memory controller.AMD processors are more expensive for 2 reasons:
- integrated memory controller takes up more die space (offset by cheaper motherboard)
- AMD is still using 90nm on 200mm wafers, while Intel is using 65nm on 300mm wafers (Intel gets more CPUs per wafer bigtime)
peternelson - Tuesday, May 23, 2006 - link
Sempron AM2 can do memory up to DDR2-667
Dualcore AM2 can do memory up to DDR2-800
However, PLEASE CHECK SINGLE CORE MEMORY SPEED (multiplier issues aside) which you say limited to 667 whereas I got the impression they can also do 800 like dualcores. Correct as necessary.
smitty3268 - Tuesday, May 23, 2006 - link
I accidentally hit the "not worth reading" button, so I'm writing this comment to undo it :)fikimiki - Tuesday, May 23, 2006 - link
There are a couple of reasons for that:- K8L photo had a Z-RAM implemented, so they are using this kind of cache for a quite long time.
- Shared L3 should help Athlon64 in matching Super-Pi and overall performance.
- Usage of Z-RAM will reduce cache die size by 75% with no architectural changes.
So FX-64 to beat fastest Core 2 just needs 4MB of cache...
Easy trick but can be useful to survive till 65nm production...
Questar - Tuesday, May 23, 2006 - link
It's not going to be Z-RAM. Z-RAM won't even be in K8L.
“We’ve looked at data from Innovative Silicon and it looks very promising. We still need to assure ourselves that this will work in our own application. We need to see how it scales and we need to make our own test vehicles,”
Jones, an executive experienced in intellectual property licensing, also declined to comment on AMD’s timetable for introduction of Z-RAM but offered a more general perspective. “In the past it has been two years from when you sign a deal to when it is in production.”
http://www.eetimes.com/news/latest/showArticle.jht...">http://www.eetimes.com/news/latest/showArticle.jht...
munky - Tuesday, May 23, 2006 - link
I think the June trick AMD will pull out is the Clearspeed coprocessor. It definitely won't affect many users, but for those who do invest in the technology, it could provide a decent boost in number crunching power.peternelson - Tuesday, May 23, 2006 - link
Clearspeed are working on being one acceleration solution, yes, but the already launched acceleration on socket 940 is companies offering plug in Xilinx4 FPGA on hypertransport.
I hope that gets re-engineered onto socket F pretty quickly. We may see announcements once socket F is actually launched in July.