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SLI and expansion cards
#380318 - 12/25/18 05:33 AM
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So, I have a z97 Gaming 7 motherboard. It has room for 3-way SLI (which I will probably never waste money on). But like all other SLI-type setups ever, using the feature drops the number of PCIe lanes. It's either 1x16, or 8x4x4. The ports in between are x1 PCIe slots.
So here's my question: If I decide to get a USB 3.1 expansion card, which requires a x4 slot, and drop it into the last full-sized PCIe slot with nothing else (other than my video card in the 1st one), will it a) WORK, and B) drop my video card down to x8? Will dropping my video card down to 8 lanes bottleneck the performance?
This stuff is confusing.
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Re: SLI and expansion cards
[Re: URherenow]
#380319 - 12/25/18 06:57 AM
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> If I decide to get a USB 3.1 expansion card, which requires a > x4 slot, and drop it into the last full-sized PCIe slot with nothing else (other than > my video card in the 1st one), will it a) WORK, and B) drop my video card down to x8? > Will dropping my video card down to 8 lanes bottleneck the performance? > > This stuff is confusing.
It varies from motherboard to motherboard. If I remember correctly, on mine there is only one other slot that shares lanes with the first slot. I don't think it's the last one. There's also a BIOS setting that forces a particular slot to use less lanes.
Your motherboard manual should have an overview of how the lanes are divided between slots.
S
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Re: SLI and expansion cards
[Re: Sune]
#380344 - 12/26/18 08:53 AM
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The PCI x16 slots only mention video cards
x16 x8/x8 x8/x4/x4
Those are the options it gives. I'm leaning towards forgetting about USB 3.1 at this point and just getting a USB 3.0 expansion for a x1 slot :/
EDIT: after looking at this, I really don't know. Perhaps the USB 3.1 would be worth it https://www.pugetsystems.com/labs/articles/Titan-X-Performance-PCI-E-3-0-x8-vs-x16-851/
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Re: SLI and expansion cards
[Re: URherenow]
#380351 - 12/26/18 06:09 PM
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> I'm leaning towards forgetting about USB 3.1 at this > point and just getting a USB 3.0 expansion for a x1 slot :/
That's what I would do.
USB 3.0 is "fast enough". How often do you copy huge files to/from an external drive, and do you stand around and wait while copying files or do you do something else?
I suppose if you work with audio or video editing professionally and move around large files every day, then you'd want external drives to be every bit as fast as possible. But if not, why bother?
S
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Re: SLI and expansion cards
[Re: URherenow]
#380436 - 12/30/18 04:10 PM
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To be honest, dropping the video card to x8 probably won't impact performance. I don't know of any games that are bottlenecked on texture uploads. If you run any CUDA/OpenCL type GPU computing that's different, but for gaming x8 is unlikely to change your framerate.
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Re: SLI and expansion cards
[Re: Sune]
#380456 - 12/31/18 05:44 AM
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Not every day, of course, but even my new profession has me deploying on Navy ships, so I do synchronize things like the entire MAME library (including CHDs and SoftwareList stuff) to an external a few times a year...
I admit though that my main reason for expansion is that for some reason the Oculus Rift recommends that no more than 2 sensors are plugged into the same USB bus, and I plan on picking up 2 extras sometime soon. I just don't like the idea of buying new computer parts that I know are already obsolete and slow before I even buy them. Sort of OCD as much as my time/money allows when it comes to computer upgrades...
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Re: SLI and expansion cards
[Re: URherenow]
#380460 - 12/31/18 11:01 AM
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> I admit though that my main reason for expansion is that for some reason the Oculus > Rift recommends that no more than 2 sensors are plugged into the same USB bus, and I > plan on picking up 2 extras sometime soon.
My motherboard has a secondary USB 3.0 controller besides the one that's part of the chipset. ASMEDIA something something.
Maybe yours has too?
S
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Re: SLI and expansion cards
[Re: Sune]
#380473 - 01/01/19 04:01 AM
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yes, but I believe it is only the internal headers that my front case ports are connected to. I guess either way, I'll have cables cluttering the floor. Gonna trip on them or snag them while playing...
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