Sockets

[THERAP1ST]

I searched AMD website for a little while but I couldn't find the answer I was looking for. What is the differecnce between a a socket 939 processor and a socket AM2 processor, other than the AM2 being newer?

 

[CrossFire851]

AM2 uses DDR2 and 939 uses DDR(1). AM2 has 15% performance increase. If you want better options to upgrade get AM2 because DDR2 is more future proof. But socket 939 is still good, but I would recommend AM2.

Do some Googling, it's your friend.

 

[fastco]

AM2 has support for DDR2 memory and will support faster chips than socket 939 will in the future.

In more detail:

The upcoming move to AMD Athlon64 AM2 will introduce a new Socket 940 design. The new Socket is very close in design to the current 940 design used on Opteron motherboards. It appears the pin-outs have been changed just enough to prevent the new AM2 processors from accidentally being plugged into older Socket 940 boards.

It was already clear the new CPU would require DDR2 memory, but it appears AMD is also using this architecture change to upgrade the current mounting scheme for Athlon 64 heatsink/fans. The new design is certainly very secure - more stable than the current design - but there are very few existing heatsink/fans that will work on the new cage. From Socket 754, 940, and 939 the same heatsinks have all worked on all Athlon 64 sockets. With AM2 that compatibility basically ends.

For those buying a retail CPU with the HSF this news won't matter at all. For enthusiasts that have invested in more exotic air, water or phase-change cooling solutions for Athlon 64 this could be important news.

Heatsink, water-cooling, and phase-change designers can make a few changes to existing designs that will allow their products to work with both the new AM2 design and the existing A64 754/940/939 design. Keep in mind, though, that it is not likely your current favorite cooling solution for Athlon 64 can go with you to the new AM2 platform.

Speculation is still circulating on exactly when the new AM2 will be launched. Several weeks ago, it appeared likely an AM2 launch would happen in the Cebit (early March) to end-of-April time frame. Announcements of delays the last few weeks now point to a July release date. Whenever the launch happens, those moving to AM2 will at a minimum need a new processor for a new Socket 940, new DDR2 memory to replace existing DDR memory for Athlon 64, and a new or revised heatsink/fan cooling solution.

 

[vnf4ultra]

AM2 uses DDR2 and 939 uses DDR(1). AM2 has 15% performance increase. If you want better options to upgrade get AM2 because DDR2 is more future proof. But socket 939 is still good, but I would recommend AM2.

Do some Googling, it's your friend.

I'd be interested to know where you heard am2 cpus were 15% faster than 939.
All reviews I've seen show approximate parity of similarly clocked processors, and in some cases, the 939 was even faster.
http://www.pcper.com/article.php?aid=252

In reality, even AMD notes that the expected performance delta between the S939 and AM2 parts with similar frequencies is only 1% and thus we should expect an AM2 4200+ to perform nearly identically to a S939 4200+.

More links:
http://www.tomshardware.com/2006/02/21/a_look_at_amds_socket_am2_platform/page12.html
http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=2738&p=4

 

[Sharkfood]

I'd be interested to know where you heard am2 cpus were 15% faster than 939.

If anything, I'd realistically expect AM2 based solutions to be a good 1-5% slower, on average, to comparably equipped socket 939/ddr systems for the time being.

While DDR2 has substantially higher bandwidth ceiling, this poses two problems for AMD cpu's:
1) AMD cpu's have been designed specifically to do more with less bandwidth.
2) Latency (which ddr2 has higher latency) has a bigger impact on AMD's than Intels.

The superior bandwidth and poorer latency make AM2 systems almost a "wash" at this point in time.

What is really encouraging is when AMD get's the time to start better utilizing the massive bandwidth now available with the AM2/DDR2 combination. Current AM2 processors are really not architecturally different to their socket 939 counterparts and therefore the extra bandwidth afforded is really going to waste right now. If they get reversed-hyperthreading working as hyped though, you can expect to see *at least* a 15% improvement in game performance, provided you have the graphics card muscle behind it to allow it.

 

[KingCody]

plain and simple...

current AM2 processors are modified 939 processors. they simply modified existing socket-939 processors with a new DDR2 memory contoller.

as stated earlier there is little performance improvement (and in some cases there's actually a loss). current high end DDR performs better on 939 than DDR2 on AM2 due to the low latency.

AMD will release the 65nm K8L series processors in a few months, that is when you will see the performance gain over socket-939. K8L has several major improvements over current K8 processors and comparible intel models (yes, this also includes conroe).

just something else to consider, there is no guarantee (that i have seen anyways) that states current AM2 mobos will support K8L processors. so buying an AM2 board now may not provide as much future-proofing as people think. they may require new chipset revisions, etc.

the future of AMD performance wise will be hypertransport-linked co-processors (CPU, video, and physics), but it will be quite some time before you see that become a reality. but when it does, it will be more powerful than any PCI-e video card system out there. ... just something to keep us AMD fanboys happy for a while