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Which is a pci-e x16 and an x8?

Hey, I'm moving my 5850 down a slot on my msi 790xt-g45 mobo... both the slots are the same size, pci-e 2.0, but I understand that one of the slots is x16 and one of them is x8... which is which?
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  1. correct me if I'm wrong, but afaik if you only use one of the pci-e slots it's always x16. Not sure, but otherwise, it's always the one closest to the CPU.
  2. Typically the one closet to the CPU is always the fastest, but your MOBO both are 16X.

    Specs -
  3. The closest PCIe x16 to the CPU is always the x16 slot first but may act as x8 in a multiple card setups depending on the board.
  4. ^ Synchronized Posting!
  5. @jaquith... The Global site says one is x16 & one is x8...

    My experience has been trust the Global site over the US site.
  6. You one that post :)
  7. tecmo34 said:
    @jaquith... The Global site says one is x16 & one is x8...

    My experience has been trust the Global site over the US site.

    okay, so uninstall drivers, switch slots, and the other slot might (should) be a little faster? I'm in the lower slot now.
  8. You don't need to uninstall drivers. Just switch slots and boot up. Also, you can download GPU-Z to verify your speed before hand on the slot (x8 or x16). Either way, I recommend running on the run closest to the CPU.
  9. Best answer
    tecmo34 said:
    @jaquith... The Global site says one is x16 & one is x8...

    My experience has been trust the Global site over the US site.

    {MSI} well that is the dumbest thing - what in the "heck" are they doing with (2)+ databases?! My assumption, "might be" that there are (2) models or MSI is really dumb. Prior to my post I looked at both Newegg + MSI; Newegg was vague/no lanes published.

    On the "positive" side even an OC GTX 480 at peak will barely max an 8X lane. However, it is best to place the GPU in the closest PCIe slot to the CPU. If it is a question or concern over NB heat then it won't matter too much; instead get better airflow in the case. In particular a "Top" vented case is best; the heat will congregate towards the top {hot air rises}. A non shrouded {non spec} GPU requires good air flow period.

    Yes, as long as the correct drivers are installed the GPU will be detected and install.

    Q&A - "Which is which" -> Top {closest to CPU/Blue} PCIe is 16X, and Bottom {Blue} is 8X ; if the Global MSI link is correct.
  10. okay... I was worried about my NB overheating before... do they make aftermarket heatsinks for them? it was hitting 60c before... is that too hot?
  11. Hey, I found a Nb heatsink... But I'm worried about it not fitting... I have a cooler master Hyper 212 plus for a cooler, and I'm moving my 5850 to the x16 slot near the cpu. Am I going to have room? I'm hoping to get the thermalright hr-05.
  12. No, 60C is not too hot for the NB, it is rated to an incredible 105C. However, 60C suggest to me poor case airflow.

    Q - What Case?
    Q - How many Case Fans are installed; e.g. 120mm front/in, 120mm rear/out, etc.?

    Suggested Tests:
    1. run Prime95 15 minutes with side panel off {post temps}
    2. cool off/shut down 10 minutes
    3. run Prime95 15 minutes with side panel on {post temps}
  13. Uh, custom case, w/ 2x120mm fans, a 140mm in & 2 80mm's out plus, there is no front... it's wide open.
  14. Ass-u-ming CFM; 240mm {IN} > 220mm {Out}; you want Negative Pressure - CFM {IN} < CFM {OUT}.

    Q - Does the case have a TOP out? My assumption is NO.

    Run the tests.
  15. Uh, they're 140 and 120... and yes, the 140 is in and the 120 is out. and it does have a top out. I build the whole thing myself... there's a 120 out on the top.
  16. This is like a word puzzle:

    1x140 mm [IN]
    2x120 mm [OUT]
    2x 80 mm [OUT]

    140 [IN] < {2x120 + 2x80} or 400 mm [OUT] ; this is not good.

    If it were 'my' rig ; I assume the case has a fail amount of meshing.
    Top = 1x120 + 1x80 mm [OUT]
    Front = 1x140 mm [IN]
    CPU {rear} = 1x120 mm [OUT]
    Panel {side} = 1x80 mm [IN]

    {200 + 120} = 320 mm OUT > 220 mm IN = {140 + 80}

    Post a picture of the case.
  17. You want air intake at bottom/front and air exhaust at top/rear.
    Side fans: if it's close to the bottom - intake, if it's close to the top - exhaust.
    Total air out should be > total air in. That way you get negative pressure inside. Cases are not airtight and they can get flow through various openings. You don't want positive pressure in the case, will mess up the whole airflow setup.
  18. ^ Side in @ NB is very good.
  19. Best answer selected by Martin 71.
  20. This topic has been closed by Mousemonkey
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