Here's the question, I have a GTX 460 and an ASUS P8Z68-M Pro. It has (2) 2.0x16 PCIe slots. According to specifications they operate at 16x and x4. Here's what's listed: Expansion Slots 1 x PCIe 2.0 x16 (blue) 1 x PCIe 2.0 x16 (x4 mode, black) *1 2 x PCI Note *1: The PCIe x 16 slot (x4 mode) is compatible with PCIe x1 and x4 devices. I posted a pic with my GPU in the "black" slot (I take it this is the x4 slot). It was mentioned that I might need to move it to the "blue" slot. Now if I want to install my Sound Card (MOBO sound went out so it is essential) I can't do it with the GPU in the "blue" slot (Sound card is PCI, but it was only $8 on clearence @ Best Buy today, so I figured what-the-heck). Sorry got sidetracked, so back to the question, I removed sound card and installed the GPU in both slots and ran benchmark tests (Cinebench 11.5, Furmark, 3dMark11) with card in each slot. The scores came up the same with the card in each slot. Does this mean that my card can't fully utilize the x16 mode or am I missing something else (meaning is there another test that would show a clear difference between x16 and x4 mode)? GPU is MSI GTX 460 Hawk Talon Attack. Here's the Specs: ModelBrand: MSI Model: N460GTX Hawk Talon Attack Interface: PCI Express 2.0 x16 Chipset: NVIDIAGPUGeForce GTX 460 (Fermi) Core Clock: 810MHz Shader Clock: 1620MHz Stream Processors: 336 Processor Cores Memory: Effective Memory Clock3900MHz Memory Size: 1GBMemory Interface: 256-bitMemory TypeGDDR5 FeaturesFeatures0.4ns Memory on board -Default GPU/Memory clock: 810/3900MHz. -Better overclocking potential. Triple Over voltage by Afterburner -The world’s first graphics card supports voltage adjustment of GPU, Memory, and PLL. -First GTX 460 can reach to 1GHz under air cooling! 7+1 Phase PWM Design -7+1 Phase PWM design provides extra 30A current output power to GPU for better overclocking power capability. Twin Frozr II Thermal Design -Nickel-plated copper Base for better heat dissipation. -18? Cooler and 8.1 dB quieter! Military Class Components -SFC (Super Ferrite Choke) has higher current for better overclocking ability. -Hi-C CAP for GPU provides more precise voltage. -All Solid CAPs have longer lifespan. Manufacturer WarrantyParts3 years limitedLabor2 years limited For what it'd worth, I know that to keep sound from my system I will have to use the "black" slot, but was just wondering what the difference is. Also mentioned on other thread was temps, but even though the black slot is closer to the PSU fan (which was mentioned because the two could be fighting for air) the temps were within 2 degrees in each position.