PCI Express on new AMD motherboards

[Only1KW]

I'm currently looking to build a new desktop PC on a budget that can handle my gaming needs currently and is possible to be upgraded in the future. Based on this, I am looking at a getting a mid-range AMD processor and a PCI graphics adapter rather than just a processor with an integrated GPU.

From my research so far, it appears that my modern AMD socket choices are AM3+ and FM2/FM2+, and that the difference is FM2 processors have onboard graphics while AM3+ processors do not and so require a PCI graphics adapter. Since I plan to get a PCI adapter anyway, it seems like AM3+ processors are the way I'd want to go for best performance / price value (on a side note, I'm specifically considering the FX-6300).

However, using the search feature in Newegg as a reference, I literally find no AMD motherboards that have both an AM3+ socket and a PCI Express 3.0 slot on them. All the AM3+ motherboards only have PCI Express 2.0 and only the FM2/FM2+ AMD boards have PCI Express 3.0 slots on them. This seems completely backwards to me since PCI Express 3.0 is mostly for graphics adapters today and the FM2 processors are the ones that don't need PCI graphics adapters. Am I missing something here?

 

[rolli59]

Correct AM3+ does not support PCIe ver 3.0 but is fully compatible since the PCIe std is backwards compatible.

 

[Only1KW]

Correct AM3+ does not support PCIe ver 3.0 but is fully compatible since the PCIe std is backwards compatible.

Thanks for your response. I do understand that it is backwards compatible, but my concern is more the performance hit that I will take as a result. When comparing benchmarks on graphics adapters, I assume they are measured in a PCI slot that matches the highest PCI version the card supports, and am not sure how much of a hit my overall gaming performance would take as a result of adding a 3.0 adapter to a 2.0 slot.

If AM3+ does not support PCIe express 3.0, then what combination am I more likely to get better performance / price value with?

1. AM3+ CPU + PCI express 2.0 graphics
2. FM2(+) CPU + PCI express 3.0 graphics
3. 1155 CPU + PCI express 3.0 graphics

Note that I am trying to keep my CPU + motherboard combo cost below $250 if at all possible.

 

[Dark Lord of Tech]

SABERTOOTH 990FX/GEN3 R2.0

Exclusive AMD PCIe 3.0 Military-Grade Motherboard with TUF Cooling Technology.

http://www.asus.com/Motherboards/SABERTOOTH_990FXGEN3_R20/

PCI Express 3.0 x16
3 (dual x16 or x16/x8/x8)

Hard board to find.

The first thing that really stands out about this model is that it is the first AM3+ motherboard to support PCIe 3.0 slots for expansion cards. The basic architecture behind the AM3+ CPU socket simply does not support PCIe 3.0, so most motherboard manufacturers do not include those slots on their boards. ASUS has developed architecture that lets PCIe 3.0 slots work on their board, and this one includes three of them in x16 mode - though if you use all three for a multi-video card setup, they run in x16/x8/x8 modes. On top of this, the board supports up to 32 GB of DDR3 1866 RAM, with numerous SATA connections for disk or hard drives. But ultimately, if you want an AM3+ motherboard with a PCIe 3.0 video card, then this model is the choice for you.

 

[rolli59]

There will be no performance hit or so to speak, last generation top cards http://www.techpowerup.com/reviews/Intel/Ivy_Bridge_PCI-Express_Scaling/23.html Maybe with the most powerful cards today running at X8 X8 on ver 2.0 in dual setup it will be noticeable but not with dual cards at X16 X16 ver 2.0 like the 990FX boards. Actually X16 ver 2.0 has the same bandwidth as X8 ver 3.0!