Socket-AM2+, Not So Positive?

When AMD first started talking about Phenom it boasted backwards compatibility with current Socket-AM2 motherboards, as well as a new Socket-AM2+ platform that would enable higher performance and better power management.

We are currently looking into Socket-AM2 motherboard compatibility, but not all vendors have Phenom-ready code for their motherboards as of today. While Phenom should work in virtually all Socket-AM2 motherboards, it's tough to say which will work by the time you can actually buy these things.


AMD's Spider platform, well, minus the graphics card - the 8800 GTX is still our testbed GPU of choice.

Socket-AM2+ motherboards, most of which are based on AMD's new 790FX chipset, were supposed to bring a tangible performance increase when paired with a Phenom processor. Phenom's L3 cache and North Bridge work on the same power plane, one separate from the rest of the CPU. Socket-AM2+ enables the use of two separate voltages, one for the L3 cache/NB and one for the rest of the CPU, whereas Socket-AM2 motherboards run the entire chip at the same voltage. The original plan was for Socket-AM2+ motherboards to run the L3 cache/NB at a higher frequency than the rest of the chip, unfortunately it looks like AMD wasn't able to make that happen.


Socket-AM2+ in action

Currently, the L3 cache/NB on these chips runs at a fixed frequency that's actually lower than the rest of the CPU frequency: 2.0GHz. We tested Phenoms running from 2.2GHz all the way up to 2.6GHz, and in all cases the L3 cache and North Bridge ran at 2.0GHz. We're not sure if this will ever get fixed, but it's somewhat disappointing as it was supposed to be a major reason for upgrading to Socket-AM2+ (but it's good news for current AM2 owners).

Right now it looks like the only benefit to Socket-AM2+ is support for DDR2-1066, which we've been having problems with internally already. If you've got a good Socket-AM2 motherboard, you may not need to upgrade to get the most out of Phenom.

First Tunisia, then Tahoe? Overclocking
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  • agello24 - Saturday, February 16, 2008 - link

    im still not ready to switch to intel. ill be buying my phenom shortly. Reply
  • GenoR32 - Tuesday, February 05, 2008 - link

    I still believe in AMD, and i know they will release a nice product line-up in the coming months, or probably 2009... i have a Core2 PC now b/c i cant deny the fact that they are really strong CPU's... but my DDR3 upgrade will be on an AM3 system... i think they will be really competitive.

    Greetings
    Reply
  • eye smite - Monday, January 07, 2008 - link

    I didn't comment on this review when it first came out cause I didn't want to read the whole thing. It reads more like a rant on a blog than a review, he didn't want to go to Cali, so what. In the time since this article the phenom has proved to be a good cpu, I noticed in the last week that HP and Gateway have started selling systems in Best Buy and Circuit City with phenoms. This cpu was rushed out and it will take a bit of time to mature. It's the same thing we saw with the athlon64 from 2k3, had it been as developed as it needed to be, they would not have gone from socket 753 to 939 to am2 and so on. Amd should have made the smaller leaps to a quad core athlon64 til phenom was ready, but they have bad decision makers these days it seems. Reply
  • Hellrazor0628 - Thursday, January 03, 2008 - link

    Well I think that intel got the processing but i realy dont think at the first place that the phenom is ready they need time and money to be able to get rev. in good working and debuged intel had that money and time they realy took their time befor shoing up with core2 wonld say tow years almost. Amd had already a small part of the market enven whene they give the best performance for the price even compaired to the best intel. To say it I realy was hoping the truth native quad core phenom would be better proccesing too but in ther other hand there are a lot of technogie that need to be looking at about amd that poeple sould take a look at about the phenom that is key to all amd cpu that people are too stupid to look at and understand. like power comp. wtf man there is a bus and a memory controler my nvidie chip set coul burn and egg and it only have to run the pci and pci-x. Reply
  • hoelder - Wednesday, December 12, 2007 - link

    I remember to have to save food of my mouth to buy the first ill conceived Pentium or the 486. How Intel set those prices evades me. They maximized their profits with no competition. Yes I know Intel produces a faster chip, if faster is the right word. However, when it comes down to competition and the markets, AMD is the strategically right choice. Unless of course you think that the Walmart buy cheap toys from China idea is your consumer ideology then you should stick with Intel, that actually is going like Nixon to China or you believe in the consumer choices should keep competition open. Reply
  • mpholland - Friday, November 30, 2007 - link

    Maybe AMD just had to release these early to make a little capital this year. Personally I think that it is good that AMD let people know SOMETHING is close. I am hoping that with a little tweaking AMD and some MB partners can get performance up a little and be competitive with Intel sometime in 2008. I have seen just simple driver tweaks work wonders on other hardware, maybe just a little more time can help. Reply
  • Clauzii - Thursday, November 22, 2007 - link

    -- Reply
  • Clauzii - Thursday, November 22, 2007 - link

    By reading through the benchmarks, where a single core (of a quad) is compared to all four cores running, it looks like the 8 core version of the "Phenom" would scale even better than the four-core one. The Barcelona btw. also shows this behavior, by having one core being just a little faster than the Opteron core, but the four running in tandem scales very well.

    Because of the not-so-good MHz numbers, it might not take AMD to new glorious heights for now, but when (soon?) 8 cores arive, AMD MIGHT be able to do better, because of their better core-scaling factor.

    Looks like they HAVE to do something like gluing together two Phenoms to at least do 8-cores before intel, and before intel gets TOO fast for AMDs liking and the ability to catch up slips away.

    Unless AMD already is working on a true 8-core design, which would probably scale even better than a glued one. And by incooperating knowledge on multithreading from ATIs designing of GPUs they might be able to do something even more serious in the future.

    But for know, intel is still in the lead.
    Reply
  • praeses - Thursday, November 22, 2007 - link

    I really wish that AMD never went down the road of L3 cache for these processors. As the majority of applications still used today in the desktop/workstation market are going to be only one or two cores, the shared cache itself probably causes more of a hindrance.

    Personally I would have liked to see 128k L1 and 1MB of L2 for the higher models, and simply the 512K L2 for the lower models. The tweaks to the individual cores would almost enable them to catch up clock per clock with Intel without this L3 cache latency getting in the way, and that way powering down the individual cores would also power down all the cache they would be using as well. I realize that routing the L2 cache in larger quantities is trickier and consumes more die space than L3 but they should also be able to gain significantly cost measures in those produced without L3 and be able to compete better in the $180 or so market.

    Granted if a single application was single threaded and the only one taxing the system while taking advantage of all the L3 at once, and the other 3 cores were sleeping, it would be a slight disadvatage, but that's an extreme situation.
    Reply
  • WorkIsAFullTimeHobby - Thursday, November 22, 2007 - link

    I think Anandtech power consumption graphs are way off. Phenom power consumption sould be compared to Penryn power consumption plus NSB power consumption. Does any body see any mention of this fact and do the graphs properly account for this?

    Phenom effectively has the north side memory controller bus built in. After looking at the Architecture now I know why Intel is always trying to increase MB bus speed. They only have one external bus to feed and comminicate between all the CPU's.
    Reply

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