AM3+ CPU in an AM3 socket?

[lordvic]

I was just browsing around on ASUS's site during my free time earlier today, and I decided to see if they got any new BIOS' for my Crosshair IV Formula (been ages since I last checked). Then under the BIOS tab:
- version 3027
- Beta BIOS
- 2011/11/18
- Support for New CPUs

I click on the CPU Support list and see...

FX-4100(FD4100WMW4KGU),3.6GHz,4C,95W,rev.B2G,AM3+
FX-4170(FD4170FRW4KGU),4.2GHz,4C,125W,rev.B2G,AM3+
FX-6100(FD6100WMW6KGU),3.3GHz,6C,95W,rev.B2G,AM3+
FX-8100(FD8100WMW8KGU),2.8GHz,8C,95W,rev.B2G,AM3+
FX-8120(FD8120FRW8KGU),3.1GHz,8C,125W,rev.B2G,AM3+
FX-8150(FD8150FRW8KGU),3.6GHz,8C,125W,rev.B2G,AM3+

Don't the AM3+ FX chips have an extra pin compared to AM3? How does it physically work on the Crosshair IV ?!?!

Can anyone actually verify that it works? I am completely lost...

Thank you!

[Apoptosis]

Socket AM3 was launched on February 9, 2009 as the successor to Socket AM2+. As you know Socket AM3 added support for DDR3 SDRAM and those processors will not work in older sockets. The newer Socket AM3+ or AM3b design that came out in October 2011 is a modification of the AM3 Socket to run Bulldozer processors. It still retains compatibility with AM3 processors.

The AM3+ Socket specification contain has 942-pins, which is an increase of one over the AM3 Socket's 941-pin. They unblocked one of the blocked off pins on the AM3 socket design, so that is how it works.

You can put an AM3 processor in an AM3+ socket, but not the other way around.

[lordvic]

But Apop, how does a AM3+ / AM3b CPU work on a AM3 socket motherboard? (Crosshair IV Formula 890FX AM3).
I don't belive ASUS made any revisions to the board - I'm pretty sure they ditched it and moved onto the Crosshair V .

[Velo:Sity]

If BIOS lists the CPU, it should work. It is a bit like putting a square peg in a round hole, but it will fit and work. It was the same with AM2+ sockets and AM3 processors, wasn't it?

[lordvic]

The extra pin found on AM3+ is located where is it "plugged up" in the AM3 socket. Wouldn't you be bending / breaking off the extra pin?

That's what messing with me right now; AM3+ has a pin where the AM3 socket does not have a hole for...

[Athlonite]

This is also what I'd like to know aswell as I'm currently running the CH IV with the latest bios

[walterm]

Before AM3+ became officially released some motherboards became AM3+ COMPLIANT. Officially you need the black CPU block for AM3+. These became available before release of FX CPUs or chipset motherboards.
If you have the black socket you are good with BIOS update.
I have heard of possible white socket motherboards being AM3+ compliant before the black sockets were available. Whether these were review samples or early production I do not know.
Query board maker for revision numbers??

[Kaos Kid]

Support for Zambezi was added for my M4A89GTD PRO/USB3 (though only with the beta bios) and mine is lower end than yours so you should be OK for FX4100>FX8150. Our boards will not take full advantage of the FX series like the 990 chips though, but should still see a boost from the Phenom II class. I already have an x6 1100T so it doesn't seem worth the money to me for the upgrade. If I decide I want to go to the latest AMD then I will just get a new mobo that will accept Vishera as well as faster memory (currently I can only use up to DDR2000), and USB3 Headers, which mine currently doesn't have (only has on back I/O).

[Progerc++]

I have never encountered this before