Asus Maximus IV Extreme PCIe usage

kakureru

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Asus Maximus IV Extreme PCIe usage​

Does anyone else have one of these who can tell me if it is possible to use non video cards in the red PCIe slots?
This board is a whole mess of weirdness. I got it thinking I can load up all available slots with TV tuners.
 

Dan_D

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Asus Maximus IV Extreme PCIe usage​

Does anyone else have one of these who can tell me if it is possible to use non video cards in the red PCIe slots?
This board is a whole mess of weirdness. I got it thinking I can load up all available slots with TV tuners.

PCI-Express compliance generally means you can use any PCI-Express compatible expansion slot with any PCI-Express compatible device. So, the answer would be yes. Although, I don't know if there are enough PCIe lanes to do what you want. I haven't seen one of those in a very long time.
 

kakureru

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PCI-Express compliance generally means you can use any PCI-Express compatible expansion slot with any PCI-Express compatible device. So, the answer would be yes. Although, I don't know if there are enough PCIe lanes to do what you want. I haven't seen one of those in a very long time.
in the real world sure, Ive done this allot on other boards with multiple PCIe 16x slots. Each one of these cards are 1x. the board will happily use 3 video cards in those slots tho. If I insert any non video card into any of the slots even if its the only other pcie card, it will not be detected by windows.
 

Dan_D

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in the real world sure, Ive done this allot on other boards with multiple PCIe 16x slots. Each one of these cards are 1x. the board will happily use 3 video cards in those slots tho. If I insert any non video card into any of the slots even if its the only other pcie card, it will not be detected by windows.

They do not have to be video cards. I've run RAID controllers, network adapters and all manner of devices on older, shittier boards. If you've got specific cards that don't behave it's not the boards fault. (Most likely.)
 
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kakureru

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They do not have to be video cards. I've run RAID controllers, network adapters and all manner of devices on older, shittier boards. If you've got specific cards that don't behave it's not the boards fault. (Most likely.)
So have I. This is what I am asking about this specific board where asus did some sort of voodoo to make the PCIe slots for many video cards. (since 1155 cpus only have 16 lanes)
edit - every 'special' slot works fine with a video card.
 

lopoetve

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So have I. This is what I am asking about this specific board where asus did some sort of voodoo to make the PCIe slots for many video cards. (since 1155 cpus only have 16 lanes)
edit - every 'special' slot works fine with a video card.
PLX chip most likely. They were more common back then, which is why the whole lane conversation (I suspect) didn't come up till more recently.
 

Dan_D

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So have I. This is what I am asking about this specific board where asus did some sort of voodoo to make the PCIe slots for many video cards. (since 1155 cpus only have 16 lanes)
edit - every 'special' slot works fine with a video card.

Again, they aren't special slots. That motherboard uses what's known as a PLX chip to add additional PCIe lanes in a sense. It's not voodoo at all as this was not only a very common practice at the time, but it was well understood by many enthusiasts and reviewers at the time. The PEX 8747 PLX chip has some 48 PCIe Gen 3.0 lanes as an example. Think of it as a PCIe expander. While the PLX chip does have extra PCIe lanes, it's still constrained by its connection to the CPU which is going to be your CPU's 16 PCIe lanes. The PLX chip adds a little bit of latency but the advantage was that you had very dynamic lane allocation which allowed for you to use multiple PCIe x16 devices in 8x or even 16x mode (depending on the configuration) and have equal bandwidth for all of your PCIe slots and devices. It allows for PCIe lane switching that you would otherwise need complicated and expensive PCIe switches for.

Issues with devices not working on a specific motherboard usually come down to OROM (option ROM) issues and firmware. Again, the PCIe slots aren't special. ASICs like the nForce 100/200 and PEX PLX chips do not create compatibility issues beyond allowing you to throw a crap ton of devices with high lane counts onto mainstream motherboards. The problem is that there are memory mapping issues with too many devices requiring direct memory access or DMA. The platform has limitations regarding this. Sometimes there were workarounds with specific firmware updates which would allow devices to behave properly in more complex configurations. In some instances, such as with NVIDIA 680i SLI reference boards that device compatibility was sacrificed to improve overclocking on the platform. There are settings you could also change or adjust which might resolve the issue. Things like PCIe spread spectrum are often disabled to facilitate better overclocks, but this can impact device compatibility. These are issues I've run into with things like RAID controllers and multiple GPU's on a single motherboard.
 
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