What's AM2?
As we've mentioned before, AMD's Socket-AM2 is a brand new 940-pin socket that will add DDR2 support for all desktop AMD processors. There will be AM2 versions of Athlon 64, Athlon 64 X2 and Sempron CPUs. All of these are internally known as the Rev F core. When AM2 launches in June, AMD will offer official support for DDR2-533, 667 and 800. As of today, the fastest DDR2 that Intel officially supports is DDR2-667; however, by the time Conroe launches in Q3, Intel will also add DDR2-800 to the list.
What this means is that if you're planning to build a new system later this year - whether it is AMD or Intel based - then you'll be in the market for DDR2 memory. AMD has effectively kept regular DDR-400 quite alive and actually created a market for even faster DDR1 memories with their Athlon 64, but after June that's all going to change. With a single memory standard to support both players in the desktop market, things are going to get a lot simpler. It will also mean that we'll start to see more focus from memory vendors on DDR2, including cheaper variants as well as even lower latency offerings. We'll address whether nor not DDR2-800 is actually needed shortly, but like it or not, if you want a solid upgrade path for the future you'll be looking at investing in some DDR2 memory regardless of whether you choose AMD or Intel.
Alongside DDR2 support, the new Socket-AM2 CPUs add support for AMD's Pacifica Virtualization technology - AMD's answer to Intel's VT. While the two technologies aren't directly compatible, given the respect that AMD has gained over the past few years you can expect software developers to support it. Virtualization will become increasingly more important as time goes on, as we have already seen in recent announcements of Intel VT support on Apple platforms.
The third thing that AM2 brings us is what AMD is calling their Energy Efficient microprocessors. Certain SKUs of AM2 processors will be binned according to their power consumption and grouped into two categories: 65W and 35W. Both TDPs, interestingly enough, are competitive with what Intel is targeting for their 65nm Conroe processors. What's even more impressive is that there will be an Athlon 64 X2 3800+ that's available at both 65W and 35W TDPs, compared to the standard 89W TDP. The chart below will give you an idea of what the new dual core AM2 CPUs are:
| CPU | Clock Speed | L2 Cache Size | TDP Options |
| AMD Athlon 64 FX-62 | 2.8GHz | 1MBx2 | 125W |
| AMD Athlon 64 FX-60 | 2.6GHz | 1MBx2 | 125W |
| AMD Athlon 64 X2 5000+ | 2.6GHz | 512KBx2 | 89W |
| AMD Athlon 64 X2 4800+ | 2.4GHz | 1MBx2 | 89W or 65W |
| AMD Athlon 64 X2 4600+ | 2.4GHz | 512KBx2 | 89W or 65W |
| AMD Athlon 64 X2 4400+ | 2.2GHz | 1MBx2 | 89W or 65W |
| AMD Athlon 64 X2 4200+ | 2.2GHz | 512KBx2 | 89W or 65W |
| AMD Athlon 64 X2 4000+ | 2.0GHz | 1MBx2 | 89W or 65W |
| AMD Athlon 64 X2 3800+ | 2.0GHz | 512KBx2 | 89W or 65W or 35W |
In the future you can also expect an FX-64 along with 5200+ and 5400+, but the chart above is what will be launching in the near future (the exception being that the 65W 4800+ that will launch in Q3).
There will also be single core Athlon 64 and Sempron AM2 processors, but we're still waiting for their confirmed specs. Given the specs of the Athlon 64 X2s, you can expect the AM2 Athlon 64s and Semprons to be identical to their Socket-939 counterparts. We'll also finally get retail availability of faster Sempron parts - current socket-939 Semprons are only available with OEM systems.
AMD has already indicated that it will not brand the 65W and 35W parts any differently than the normal 89W Athlon 64 X2s; they will simply have a different part number and carry some sort of lower TDP designation on their box. Of course, they will almost certainly carry a price premium, so that at least should help to differentiate the models somewhat.
As far as major architectural changes go, we haven't been able to find any surprises in any of our AM2 samples. L1 and L2 cache latencies remain unchanged from their Socket-939 counterparts.
You will also notice that AM2 and Socket-939 CPUs appear to carry the same model numbers, meaning that an AM2 X2 4800+ runs at the same speed and has the same cache size as a Socket-939 X2 4800+. Either AMD is being very conservative with its model numbers or we shouldn't expect to see any major clock-for-clock increase in performance with AM2 processors.
Facebook
Twitter
RSS
107 Comments
View All Comments
mino - Tuesday, April 11, 2006 - link
1) 3-cycle L1 on K7/K8 is the fastest required, it goes from the internal structure if the scheduler and the pipeline that 2-cycle chache would do almost no good. Also they would have to reduce L1 size to 32k+32k which would hurt. It simply does not make sense to change L1 at all, maybe on K8L but IMHO 128k+128k would help much more than 2-cycle latency.2) 17-cycle L2 is PRETTY GOOD for 1M L2 with exclusive structure!!! IMHO it is possible to do 16-cycle, maybe 15, but nowhere near Dothan's 10-cycle. Also remember lower-latency L2 has scaling problems (that's why intel made prescott's L2 slower than NW's)
3) Concerning the memory subsystem(caches + memory) (on single-socket K8/K8L) the biggest issue is the robustness(amount of on the fly acceses to memory) and latency of the memory controller. To solve this is not trivial thing. IMHO to add 2-4M L3 with random access ~50 cycles would do.
4) In the >4 sockets front all they need is effective caching of MOESI snoops.
You are also forgot K7/K8 is mostly KISS architecture. It is just wery well balanced so has good performance in the end. However do one wrong change and you are screwed.
KISS == Keep It Simple Silly
About "weak" SIMD implementation on AMD, don't fool yourselves guys. Only x86 architecture faster than K8 on SSE/SSE2 is Netburst aka SIMD-by-intel.
About conroe, ita has twice as wide ALU's and FPU's than PIII/K7/K8, this means it has huge resources at disposal to calculate SIMD.
Same goes for K8L 2 quarters later. That said K7/K8 core has far more FP power than P6 architecture. On FP Conroe and K8 are about aquall.
but K8L will wipe the floor with K8 and Conroe on FP. Conroe will wipe K8 on INT and be still faster than K8L by decent margin.
Overall we are for another PIII vs. K7 battle with single very important change - AMD has a platform it had not back in the K7 vs. PIII days.
fitten - Thursday, April 13, 2006 - link
I find the K8L a somewhat odd strategy. I guess they are targeting the Itanium market because Opterons already have a good part of the HPC market. Given that the HPC people are the ones that really care about FPU performance and that they are still a fairly small market segment, it seems an odd target. Integer performance rules the roost for servers... web, database, and just about everything else you can think of other than number crunching simulations and the like. Desktop uses for FPU are a few like games and some mathmatical stuff. Intel is focusing on integer performance at least as much as FPU with Conroe (Conroe gets a good dose of both), which makes sense to me since so much of the work done on computers, both desktops and servers, is dominated by integer operations. K8L speculation says only FPU horsepower will be added... just doesn't seem like a sound decision to me.Zoomer - Monday, April 10, 2006 - link
Hey anand, could you take out 1 of the two modules and do a quick test on that?With doubled (in theory) bandwidth with ddr2, wouldn't the dual channel mem controller be even more redundant? Perhaps we'll see a new 754-ish socket? :)
Zoomer - Monday, April 10, 2006 - link
Hey anand, could you take out 1 of the two modules and do a quick test on that?With doubled (in theory) bandwidth with ddr2, wouldn't the dual channel mem controller be even more redundant? Perhaps we'll see a new 754-ish socket? :)
Furen - Monday, April 10, 2006 - link
I dont believe we will. Even S1 will be dual-channel, and this is what would have benefited the most from being single-channel (since the pincount would be much lower the package could be much smaller).BaronMatrix - Monday, April 10, 2006 - link
Looking at the intensive timing and bus speed tweaks USING the SAME RAM as the latest XE955 article I would have expected the same kind of thing here. Anand doesn't look at lower speed lower latency for whatever chip he used. That RAM will do 3-2-2 at 667. Obviously AMD is more sensitive to latency.ChristTheGreat - Monday, April 10, 2006 - link
AMD is sensitive to latencies, cause of the memory controller. I'm sure that 3-2-2-9 DDR2 from OCZ, would give much more performance on AMD.Again, this is only a CPU that they use to test, so it's not the true CPU. They wouldn't give us the performance it gives before it's launch. That's like killing yourself right now if the performance is poor....
I saw an article, that AMD could be working on DDR2 latencies. You think that 4-4-4-12 is good timings? 12 = tRAS
"tRAS is the time required before (or delay needed) between the active and precharge commands. In other words, how long the memory must wait before the next memory access can begin."
In fact, you have better frequencies, but lower timings.... What you need, is higher frequencies, and lower timings.
So we will have to wait till they launch Socket AM2, to know the true performance of AM2.
defter - Monday, April 10, 2006 - link
4-4-4-12 are good timings, even for DDR2-667. It isn't easy to find reasonable priced DDR2-667 that works on those timing with standard voltage.
Some people forget that 99% of consumers won't be using super expensive overvolted 3-3-3-10 DDR2-800 memory just to get few percents of extra performance. And if you compare AMD CPU + super fast DDR2-800 against Intel CPU (which runs fine on DDR2-667 because of FSB limitation) then you need to take into account higher price of memory on AMD system.
Wesley Fink - Monday, April 10, 2006 - link
We are continuing to test the AM2 on different AM2 boards. On another motherboard we could run at 3-3-3 DDR2-800 with the OCZ PC2-8000 memory. Latency was a bit lower and bandwidth a bit higher, but nothing realy changed from Anand's conclusions. We have also been running DDR2-667 and DDR2-533 tests with this new super fast OCZ memory and cheaper mainstream DDR2 memory, and we will be sharing those results as soon as testing is complete.cornfedone - Monday, April 10, 2006 - link
The crap the mobo companies have been shoving out the doors the past couple years is pure garbage as any number of hardware review sites have confirmed. It looks like the AM2 mobos might be more half-baked crap. Until you can test the shipping CPUs on a quality mobo that allows proper memory timing, it's difficult to know what AMD's AM2 CPUs will or won't deliver. If I had a dollar for every bogus claim Intel has made, I'd be a Billionaire so I wouldn't hold my breath that Conroe will perform as Intel claims.