GeForce And Radeon On Intel's P67: PCIe Scaling Explored

Are Sixteen Lanes Enough?

Tom's Hardware's Three-Part, 3-Way Graphics Scaling Series

Part 1, The Cards: Triple-GPU Scaling: AMD CrossFire Vs. Nvidia SLI
Part 2, The Slots: GeForce And Radeon On Intel's P67: PCIe Scaling Explored
Part 3, The Chipsets: P67, X58, And NF200: The Best Platform For CrossFire And SLI

We’re constantly impressed by the performance of Intel’s latest processors, which offer both higher IPC (instructions per cycle) and better overclocking headroom than anything seen previously. This is particularly true in games, where the extra execution resources in Intel's Core i7-990X go unused anyway.

Yet, in spite of the Sandy Bridge architecture's superior gaming performance (or at least better value, since you don't need to spend $1000 on a six-core processor to get equivalent frame rates), many enthusiasts insist on the added expandability of the old LGA 1366 platform. This makes sense in light of the P67’s incredible handicap: namely its 16-lane processor-based PCIe graphics interface.

But do we really need more than 16 lanes? Aren’t eight lanes enough for a single card? If that’s true, expensive and power-robbing PCIe bridges certainly wouldn't be necessary to support multiple cards. We’ve even heard stories that the PCIe 2.0 x4 slot supported through the P67 chipset is adequate for some graphics cards.

Before we move on to see how the P67-based platform stands up against the X58- and NF200-enhanced versions of both, let's get to the basics of PCIe scaling using modern cards on the best-possible gaming processor. This is Part 2 of our multi-card scaling series, but will there be enough graphics performance difference between various slots to justify a Part 3?

Thomas Soderstrom
Thomas Soderstrom is a Senior Staff Editor at Tom's Hardware US. He tests and reviews cases, cooling, memory and motherboards.