Overclock.net banner

confused about am2 am3 socket cpu's

360 views 13 replies 6 participants last post by  1216 
#1 ·
i bought a bunch of older amd cpus to benchmark some am2,am2+,am3. i have a 790fx board for am2/am2+ cpu's and a newer 970 board for am3/am3+ cpu's. heres where i'm confused. lookiing at cpu worlds website some phenom II and athlon II cpus are listed as am2/am3 while the ones that are listed on my motherboards support list are shown as am3. does that mean the ones listed as am2/am3 will work on either board? im confused.
 
#2 ·
Not quite.

The Phenom II series was available in an AM2+ package or an AM3 package.

The Athlon II series was/is available in an AM2+, AM3, FM1 or FM2 package.
 
#3 ·
The way motherboards listed support for AM3 processors was a bit confusing.

The 790FX (750SB) came out before the Phenom II and later ones became fully compatible with the AM3 PII and DDR3 memory using socket Am3. I ran my Phenom II on an Asus M4A79XTD EVO it's entire life.

As for AM2 and AM2+ chips, they are both the same 940 pin socket with AM2+ adding support for split power planes and HyperTransport 3.0 (very nice boost in front side bus). You CAN use an AM2+ CPU in an AM2 motherboard but it will run with a reduced FSB. You CAN use AM2 chips in an AM2+ motherboard as long as the bios supports it.

AM3 added 1 more pin (941) pins for what I'm pretty sure was to just block AM2/AM2+ CPUs from fitting in the socket. Of course, AM3 CPUs will fit in an AM2 socket and work provided it has bios support.

Hope this mess makes sense.

So I'm guessing your issue is which board your Athlons will require,

AM2+ Athlons and Phenoms will fit the AM2+ 790 chipset, but NOT the later AM3 versions.

If you see them listed here they will fit the AM3 socket:
https://en.wikipedia.org/wiki/List_of_AMD_Phenom_microprocessors#Athlon_X2_series_.28Phenom-based.29

Checking your Phenom II CPU: (you'll note that there is only one AM2+ version for each core count, so chances are yours are AM3)
https://en.wikipedia.org/wiki/List_of_AMD_Phenom_microprocessors#Phenom_II_series

Trying to find a similar list for Athlons. But you should get the idea.
 
  • Rep+
Reactions: ried16
#5 ·
the way i categorize AMD is DDR2 support and DDR3 support and i find that to be easier. AM2/AM2+ is DDR2 at max and AM3/AM3+ supports DDR3 only. As far as i am aware all phenom II's have a DDR2 and DDR3 memory support.
 
  • Rep+
Reactions: ried16
#6 ·
Quote:
Originally Posted by ried16 View Post

well i have a phenom ii x2 550 and a 555. my asus 970 pro gaming aura says it supports the 550 but doesnt list the 555. it lists the ii x3 740 but not the 720. but your link says those are all am3 cpu's. thats where i'm confused.
Ok I see what the issue is here. Let's see if google can help us with this
redface.gif
.. I'm not sure out of memory.

I also wonder if the AM2+ and AM3 models are both 938-pin and would fit either board? I was always under the impression that AM2+ will not fit socket AM3 but cpu-world lists both chips with the same 938 pins.. Obviously the AM2+ chips wouldn't have a DDR3 memory controller
 
  • Rep+
Reactions: ried16
#7 ·
It seems to me that the Phenom II 950 and 955 are both AM3 socket CPUs with DDR3 memory controllers. The reason they are listed as AM2+/AM3 is because the AM3 chip fits in either socket, but they are in fact AM3. So the issue with your specific board is that the spec sheet just doesn't have the 555 because it wasn't officially tested.

I'm pretty sure they are both the same exact CPU but the 955 is running 100 mhz faster (3.2 ghz). If the 550 works the 555 should hopefully run as well, maybe it will just think it is a 550. They should both work in the 970 pro gaming aura, and may also work in your AM2+ 970 board as well depending on the bios.
 
#8 ·
It has to be am3 or higher to work on the 970 board. The am2 cpu's wont work on the 790fx unless it is a ddr2 790fx board. But the am2+ and am3 should work on any 790fx board.
 
  • Rep+
Reactions: ried16
#9 ·
cpu-world.com lists memory controller info

Here's what it says for 550:
The number of controllers: 1
Memory channels: 2
Channel width (bits): 72
Supported memory: DDR2-1066, DDR3-1333
DIMMs per channel: up to 2
Maximum memory bandwidth (GB/s): 21.3

And here's 920:
The number of controllers: 1
Memory channels: 2
Channel width (bits): 72
Supported memory: DDR2-1066
DIMMs per channel: 2
Maximum memory bandwidth (GB/s): 17.1

If it supports DDR2 and DDR3, they work in both boards
If it supports just DDR2, it only works in DDR2 boards

There are 790fx boards with both memory configurations, I guess you know which your 790 supports.

I think the only Phenom ii's which just had DDR2 support were the 920 and 940BE. Athlons, that i don't know about

If the board lists 550 and not 555, you need to check whether there have been bios updates for C3 stepping. They have a different CPUID, 100F42 and 100F43. I'm guessing the board goes by that to start it up and the rest is on the chip itself, multipliers etc. Could work regardless but you never know
 
#10 ·
Beautiful work 1216. I think that should solve it.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top