 koitsuPremium,MVM
join:2002-07-16
Mountain View, CA
kudos:19
2 edits | reply to me
Re: Using only the second PCIE x16 same speed ? for video card Always refer to the manufacturer's web site + user manual for details of this nature.
quote:
2 x PCIe 3.0/2.0 x16 (x16 or dual x8) *3
1 x PCIe 2.0 x16 (x4 mode, black) *4
*3: PCIe 3.0 speed is supported by Intel 3rd generation Core processors.
*4: The PCIe x16_3 slot shares bandwidth with PCIe x1_2 slot. The default setting is x2 mode. Go to the BIOS setup to change the settings.
And of course a motherboard photo.
You need to refer to the User Manual to know where the x16_1, x16_2, and x16_3 slots are. They are labelled on page 2-2 (PDF page 22).
Simply put, this means (please read slowly, do not skim):
1. The dark blue and white/grey PCIe x16 slots support PCI Express 3.0 and 2.0
2. The dark blue PCIe x16 slot runs at x16 speed if the white/grey PCIe x16 slot is not populated, otherwise it runs at x8 speed
3. The white/grey PCIe x16 slot runs at x16 speed if the dark blue PCIe x16 slot is not populated, otherwise it runs at x8 speed
4. The black PCIe x16 slot supports PCI Express 2.0 and runs at a maximum of x4 speed (e.g. if a PCIe x16 card is inserted into this slot, it will only run at x4 speed)
5. The black PCIe x16 slot and white/grey PCIe x16 slot share bandwidth (limited to x2 speed).
So simply put: you can safely put your video card in the white/grey PCIe x16 slot and use it without any performance hit.
However, if you put anything in the dark blue PCIe slot then your white/grey PCIe slot will run at x8. If the card in the dark blue PCIe slot happens to be something lower than x8 speed, I'm under the impression that only that slot/card will run at that speed. Meaning: if you had a x1 speed card in the dark blue slot, and a x16 speed card in the white/grey slot, then the dark blue slot would run at x1, and the dark blue slot would run at x8.
Also, if you put anything in the black PCIe slot, then your white/grey PCIe slot will share bandwidth with the black slot (limited to x2 speed).
My recommendation: keep your video card in the dark blue x16 slot. The remaining slots you should use for PCIe x1 cards should be either (a) the PCIe x1 dark blue slots, or (b) the black PCIe x16 slot. Otherwise you will suffer speed/performance hits.
In effect, the motherboard manufacturer did not wire enough physical lanes to maintain this number of PCIe slots, so lots of slots end up "sharing" things. This is very common.
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Making life hard for others since 1977.
I speak for myself and not my employer/affiliates of my employer. |
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 El QuintronResident Mouth BreatherPremium
join:2008-04-28
Etobicoke, ON
kudos:2 | That was a great writeup BTW... |
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koitsuPremium,MVM
join:2002-07-16
Mountain View, CA
kudos:19 | Thanks. I hope I got it all correct/right! I might be misunderstanding something about the "shared bandwidth" between the black and white/grey slot, but the rest should be correct for sure. 
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Making life hard for others since 1977.
I speak for myself and not my employer/affiliates of my employer. |
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 me
join:2002-12-08
Iapetus | Thanks for the explanation. Reading it without the pic the first time was a bit confusing
To sum it up, whether I use the first or second PCIe x16 slot, adding anything to the free slot will reduce the speed.
Is the first or dark blue slot immune to this effect? Can I put a PCIe x1 card in the second PCIe x16 (grey) without degrading the speed of the primary PCIe x16 slot (dark blue)? |
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