Painfully Backwards Compatible

AMD’s big selling point of its Socket-AM3 processors is that they can still be used in Socket-AM2+ motherboards. In other words, you can use them in DDR3 or DDR2 motherboards. There’s a catch - the Phenom II X4 955 needs a BIOS update to work properly. And guess what? Not all motherboards have that BIOS support yet.

It’s not a major change but the fact of the matter is that AMD and its board partners have not done the work necessary to enable support across the board at launch. That means that if you have a Socket-AM2+ board, you may not be able to run the Phenom II X4 955 just yet.


I ran into this problem with my AM2+ testbed. For the past couple of AMD reviews I’ve used MSI’s DKA790GX Platinum, a 790GX based motherboard. AMD actually sent me the board with my first Phenom II X4 940. Unfortunately it doesn’t have an updated BIOS, so the 955 only runs at 800MHz and won’t POST at 3.2GHz. Great.

The following AM2+ boards currently have support for the 955:

Motherboard Socket Chipset BIOS Version
ASUS M3A79-T Deluxe AM2+ AMD 790FX 20090330 0803
DFI Lanparty DK 790FXB-M2RSH AM2+ AMD 790FX 200900327*
ASUS M3A 78-T AM2+ AMD 790GX 20090401 0903
Gigabyte MA790GP-DS4H AM2+ AMD 790GX 20090407 F4*
*These boards still have some known issues with the Phenom II X4 955


And more are coming. AMD suggests that you look at its Motherboard Compatibility page before you pull the trigger if you’re looking to put one of these chips into an older board.


Even Socket-AM3 boards will need a BIOS update but those seem a bit more ready to go. Unfortunately because of all of this board switching, some of my 955 numbers aren’t exactly comparable to my older 940 numbers. I’m using different motherboards (Socket-AM3 vs. AM2+) and different memory (DDR3-1333 vs. DDR2-1066). The numbers are close enough, but there were a couple of situations where performance scaled more than it should have or went negative.

Overall it’s not a huge deal but it’s frustrating for anyone looking to save money and upgrade to the 955 but using an older motherboard.

Index The Move to DDR3: You Can Do It


View All Comments

  • poohbear - Thursday, April 23, 2009 - link

    hey, is it safe to conclude that since farcry2 shows a 5% increase going from ddr3 1066 to ddr 3 1333 & another 4% going from ddr 3 1333 to ddr 1600, that overall it'd show a 9% increase switching from ddr1066 to ddr1600? that's quite a leap just based on memory! Reply
  • lopri - Thursday, April 23, 2009 - link



    Once again

    Next up (my guess): SSD or Mac
  • aguilpa1 - Thursday, April 23, 2009 - link

    Unfortunately - at 3.2 it can't keep up with 2.66 i7
    Sadly - AMD needs new architecture
    Unlikely - that it will happen soone
    Disappointing - results even though quality is improving
    Useless - to keep comparing the lates amd to intel
    Waste - of article space for these comparisons
    Unpleasant - to AMD fans
    Painfully - obvious AMD is far behind
    Negligible - improvements with new releases


    Luckily - there are other articles to read
    Thankfully - I don't own one of these chips or mobos
    Great - bunch of useless data
    Possibility - AMD may pull something actually new of these days
    Benefit - of better pricing and competition
    impressive - how I'm still finding things to write on this
    Once again - I am bored by a Tom's article
    Surprise - (sorry no surprises here)
    Refreshing - my post has come to an end.
  • Nfarce - Thursday, April 23, 2009 - link

    Hahaha! I'm still waiting on the AMD whiners complaining of Anandtech anti-AMD bias every time Intel whips them. Reply
  • Nfarce - Thursday, April 23, 2009 - link

    Oh yeah, and the fact that a stock i7 has Turbo Mode is fair game. AMD needs to produce better than this. They own the mid-range GPU market with excellent cards like the HD 4870, but their processor development just - flat - needs - help. Reply
  • Procurion - Thursday, April 23, 2009 - link

    Not an issue-I own both AMD and Intel systems but am considering moving up from my 9950BE to the 955 and want to be sure of what I am buying before I spend my money. Some of us aren't as well versed as others in the finer points and that's what I thought the comments section was for. Reply
  • Procurion - Thursday, April 23, 2009 - link

    I can understand some of your comments, but according to his data/listed values, the i7 920 is NOT running at stock speed. The frequency he lists is 2.8, NOT 2.66. What's up with that Anand? I can't see where you mention that your test was run with OC'd cpu's but the speed you list for the i7 920 is overclocked? It does skew the results if that is the case. Reply
  • Procurion - Thursday, April 23, 2009 - link

    To clarify, the listed speeds for Sysmark, which would make the i7 part look much better than if you had run it at 2.66. To draw the conclusions at the end of your article without noting the difference(if there is one and it's not a typo) or justifying your conclusion with proper references of performance in 50% of your published tests is confusing to say the least. Can you clarify? Reply
  • Spacecomber - Thursday, April 23, 2009 - link

    I'm guessing that he is showing the processor's actual speed during the test. The 2.8GHz speed likely is due to the i7's native ability to overclock itself via Turbo Mode (see page 4 of the article). In other words, the i7-920 dynamically has an actual clock speed up to 2.93GHz, depending on the application(s) running. Reply
  • Anand Lal Shimpi - Thursday, April 23, 2009 - link

    woops, sorry for the confusion there, the i7-920 ran at its stock speed of 2.66GHz but Turbo Mode was enabled so it'll run as fast as 2.8GHz when more than one core is active.

    Take care,

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