Socket 939/940 difference?

[TheGreatSatan]

Any performance difference between the Socket 940 and 939?

[INvaderEvan]

939 is newer and more cips can be put on 939 boards... 939 replaced 940 and 754

[Starbuck3733T]

939 is for athlon 64...

940 is for opterons and (I may be wrong) athlon FXs

[Greeny]

The FX come in 939 and 940 packaging now. I believe the 940 pin chipset needs registered DIMMs, taking that fact into consideration I suppose the 939 is the better of the two.

[cools]

<whispers>940 all the way, you know you want duals</whispers> ;)

[TheGreatSatan]

I already have the Gigabyte K8NNXP-940 and the socket 940 FX-51, but was just wondering about the performance diffence. I assume that the 940 is better because of the server like configuration and their ability to handle stress.

[Fibbles]

Socket 754/940/939 are all for AMD 64 branded CPU's. The FX and Opteron lines are still AMD64 bit and are intended as server based operations. Socket 754 is the lower end, I think it might only support single channel RAM too, but I'm not 100% sure. Socket 940 is the main server series, supporting ECC RAM and Opterons, as well as FX's with a single channel RAM controller. Socket 939 is newer and supports dual channel as well as non ECC RAM. Another difference is the amount of pins on the board. The 754's will turn into the value segment, while the 940 will be touted as the server section (if it isn't discontinued) and the 939's will hold the performance and high end lines for enthusiasts. To which is better, I'd guess it depends on what you're planning to throw at it. From testing of Doom 3 across all platforms, a socket 939 equipped AMD64 fared better, usually slightly edging out the 940 because of the dual channel RAM capability. I'll look for that article and post it here when I find it.

[Darv]

940 is being discontinued to make way for 939. It's more cost effective because of not needing registered RAM and there are other reasons for it.

[bigZ]

There is a mixed bag of replies here, so I'll attempt to clear a few things up....

Socket 754 is destined to become AMD's "value" socket, however this may change, as there are Socket 939 Sempron-based CPU's roadmapped. There will be no more Athlon 64's released on this socket - the highest is a 3700+.

Socket 939 is the mainstream socket for the Athlon 64, it houses both the Athlon 64, and also the Athlon FX. Later on, as aforementioned, the Sempron is likely to feature on this socket at some point in the future.

Socket 940 was where the Athlon FX was initially introduced, using the same packaging as the Opteron. There's a requirement on Socket 940 for Registered DIMMs to be used, these cost considerably more than your standard "performance" unbuffered DIMMs. The Athlon FX is no longer available on Socket 940 - the motherboards cost a lot more, along with the added cost of registered memory. This is due to the fact that the Socket 940-based boards are of a 6-layer construction as opposed to the 4-layer construction that is used on Socket 754/939 motherboards.

Socket 940 will not be discontinued - the Opteron is still moving along very convincingly on this socket. There's no need to change the socket for an Opteron, as server boards are designed for stability over performance. 6 layer construction is almost a requirement rather than an added extra (as they say).

6-layer boards offer this at a slightly higher price point, potential performance increases aren't quite the same due to the fact that there are more "wires" and layers on the board, that will essentially hinder the boards' overclockability. 4-layer boards tend to overclock much more convincingly, while remaining at a very competitive price point, and also costing considerably less to manufacture - this suits the mainstream a little better.

With regard to the performance... the Socket 939 board should perform slightly better if exactly the same chipset is used, as there's one less clock cycle for the memory to complete when reading data. Every time data is read from memory, or written to memory, the DIMMs complete an extra "registered" memory cycle. Theoretically, running at CAS2.0-2-2 on a Socket 940 board is actually running at CAS3.0-3-3, whereas a Socket 939 board remains at 2.0-2-2.

Socket 940's chipsets aren't being updated quite so fast as the chipsets for Socket 939, too... I haven't seen any K8T800 Pro-based motherboards on Socket 940, although I haven't actually hunted out every single socket 940 motherboard. AFAIK the fastest Socket 940 board is the SK8V, based on the VIA K8T800 chipset.

If you're after performance, you are better off heading towards Socket 939, but you cannot just snap a pin off, as the pinouts are totally different on the two packages ;)

http://bit-tech.net/images/review/319/939pins-2_01.jpg http://bit-tech.net/images/review/319/939pins-2_01-over.jpg

[Darv]

Thanks for clearing that up. :D

[cools]

Surely that last sentence should be "if you're after performance go for nice couple of 940 sockets on the same board" ;)

[Starbuck3733T]

its like playing where's waldo with the extra pin.

[Fibbles]

its like playing where's waldo with the extra pin.
/shrug. I found it really fast. I think I'm defective or something ^_^

[bigZ]

Surely that last sentence should be "if you're after performance go for nice couple of 940 sockets on the same board" ;)

I should have said if you're after performance from a single node, look towards socket 939 ;)

:p

[TheGreatSatan]

So I should've waited instead of just buying the socket 940 FX-51? Damn.