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PCI-X x16 and x8??

Discussion in 'Motherboards & Memory' started by Jeff574, Dec 2, 2008.

  1. Jeff574 New Member

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    hey is there a way to tell if a mobo runs its SLI slots (duals) both in x16 mode? Im on new egg and some say itll support 1 x16 and one x8, but if thats the case why does it have say 3 x16 slots? and some dont even specifiy at all :0 maybe you can make a slot thats operating at x8 operate at x16??


    thanks!
     
  2. James1991

    James1991 New Member

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    3 x16 slots mean they are the full lenghth slots. the only way you are going to tell what speed they run at is look on the manufacturers website or make a thread on here asking who has one and what speed they run at.

    you can usually make them run slower but never faster than what is specified.
     
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  3. Jeff574 New Member

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    rgr, thanks man :)
     
  4. Tatty_One

    Tatty_One Super Moderator Staff Member

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    Or....to make it simple, if you are considering Xfire or SLi which I assume you are hence the question, it goes something like this in chipset terms.............

    P35 = PCI-E 1.1 and 16 x 4
    X38 = PCI-E 2.0 and 16 x 16
    P45 = PCI-E 2.0 and 8 x 8
    X48 = PCI-E 2.0 and 16 x 16

    Nvidia 650 = PCI-E 1.1 and 8 x 8
    Nvidia 680 = PCI-E 1.1 and 16 x 16
    Nvidia 750 = PCI-E 2.0 and 8 x 8
    Nvidia 780 = PCI-E 2.0 and 16 x 16
    Nvidia 790 - PCI-E 2.0 and 16 x16

    There are a couple of boards that differ in as much as they provide say 16 x 16 when the reference spec might be 8 x 8 but largely the above stands.

    ALL RUN 16 X SINGLE SLOT normally.

    I think thats right :eek:
     
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  5. Jeff574 New Member

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    yea like i plan to buy one GTX260 right now then later on im going to buy another and SLI them.. i know i want them both to run at x16 speeds... the asus board p5n-d runs 16x16 but its getting horrid reviews on newegg, and since im kind of a novice user and never OCed anything in my life except a x1950pro i figured steer clear haha right now im eye balling EVGA 132-CK-NF78-A1, its a 780i board.. kinda pricey but im still in my limits of 1000 bux..
     
  6. Tatty_One

    Tatty_One Super Moderator Staff Member

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    What chipset and therefore price are you considering, I had an SLi rig recently so am pretty much upto speed, I would recommend the 790i if you can afford it but there are a couple of decent 750i's that clock pretty well if you are on a budget like the EVGA and MSI Platinum.....even in 8 x 8 you get good performance on PCI-E 2.0.

    Personally I would never pay "pricey" for a 780 board.
     
  7. Jeff574 New Member

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    its 215 bux lol, but yea i think 790i is a little bit out of my range, Im looking to spend in the 1000 dollar range.. right now i think it got a pretty good set up picked out.. i keep switching things around tho, i did have a cheaper mobo ($104) p45, and a HD4870 1GB picked out, but a couple recent head to head reviews i seen put the GTX260 in the top spot, it beat it out in every test :)
     
  8. Asylum

    Asylum

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    Jeff574 says thanks.
  9. Tatty_One

    Tatty_One Super Moderator Staff Member

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  10. technicks

    technicks

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    What about my board? I have a MSI P45 Neo2 FR (Crossfire)
    The specs say:

    PCI (32 Bit) 2
    PCIe x1 2
    PCIe 2.0 x16 2

    Or is it when cards put in Crossfire they work at 2 x 8?
    That would really suck because i bought this board for Crossfire and really thought it supported 2.0 x16 for both lanes in Crossfire.



    NOT:banghead::banghead::banghead::ohwell:
     
    Last edited: Dec 2, 2008
  11. Sonido

    Sonido New Member

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    PCI-X is the 64-bit version of the PCI slot. I believe you wanted to mention the PCI-E (PCI-ex) slot.
     
  12. spearman914

    spearman914 New Member

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    +1 on FTW. Extremely cheap price and a lot of good reviews.
     
  13. Tatty_One

    Tatty_One Super Moderator Staff Member

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    Standard P45 using 2 slots = x8 but unless you have two HD4870x2's there is little performance difference with PCI-E 2.0 as there is so much bandwidth available in any case., although the more powerful cards the higher the performance hit generally but we are talking like 2-5% across the board here I think.
     
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  14. Jeff574 New Member

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    so the 750i FTW is 16x16?? sweet... i was only getting the 780i for the 16x16 application.. i will probably go with that then.. its cheaper too.. theres no performance diffrence in the 780i chipset vs. the 750i right??
     
  15. wolf

    wolf Performance Enthusiast

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    i would go the 750i FTW, 16x-16x is spot on, and its still DDR2, which means lots of dirt cheap ram, which IMO is much better than not much expennsive DDR3, which unless you go for 1600+mhz, wont really give you anything more than good 800-DDR2, hec even 1066-DDR2 is nice and affordable.

    and to answer your question, if you put the same components on a 750i and 780i (ie same CPU and RAM) they should perform within a % or 2 of each other, which is nada really.
     
  16. Jeff574 New Member

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    yea im going to use OCZ reaper 1066, gettin 4 gigs of it for like 74 bux, and with the mail in rebait there only like 44 bux! what a steal!
     
  17. wolf

    wolf Performance Enthusiast

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    i recently dove on 8 gigs of 1066, that and my P45 + 3.2Ghz Q6600 should be a decent base for high end gfx for a year or so more.... @ 1920x1200 anyway, where on max settings your not really looking at a CPU bottleneck for 1 mid-high end gpu.
     
  18. Jeff574 New Member

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    not to shabby man, this is my first time building a whole pc, my budget right now is 1000 bux, heres what im looking to get right now..


    750i FTW mobo
    GTX260, 216core, superclocked addition
    E8500, going to try and have a 4.0 gig 24/7 clock
    OCZ HPC reaper edition 1066mhz (2x2gb sticks)
    Corsair 750W PSU, single 12v rail
    Western Digital Caviar 650gb 7200rpm
    Samsung 22x DVD-r with light scibe
    ???? Case...

    i need a case but no biggy right now im sitting at 850 bux... :D
     
  19. DaMulta

    DaMulta My stars went supernova

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    Easy way to remember.

    2 cards = 16x

    3 or more = 8x
    --------------
    1st 16x slot from the cpu =16x

    2ed 16x slot from the cpu =8x

    3ed 16x slot from the CPU= 16x

    4th 16x slot from the CPU =8x
    -------------------

    If its only two slots on the motherboard. Then they are both 16x in speed (these days).



    Can you tell a difference NO
    (not yet at least maybe with 2 4870x2 cards but even then.....)


    If your on a AMD chipset(AMDcpu) you could run your cards with no wires, and do everything on the 8x buss. No slow downs.

    I kind of like running my cards one down and not on the top. Makes it easier to work inside the case:)
     
    Last edited: Dec 3, 2008
  20. wolf

    wolf Performance Enthusiast

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    very nice, i like every choice except i would go a Q6600 or Q9300/9400, as even quads OC very well and anything above 3ghz is gaming bliss.

    also you could save a few more $$$ and go the stock clocked GTX260, more room for you to do your own overclocking, that is, unless the price difference is really small, cos sometimes they get the better binned chips for pre-oc models, at least thats how they should do it....
     
  21. Jeff574 New Member

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    how come you would do a quad core?? i thought games didnt use over 2 cores?

    but thanks :)
     
  22. DaMulta

    DaMulta My stars went supernova

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    Windows use more cores. When you go quad it's hard to go back.

    + DX11 coming up will take advantage of those cores more:)

    It's the only way to fit the new API into 360,wii, ps3, and PC at the same time.
     
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  23. Jeff574 New Member

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    really? nice... whats API?? and DX11 is coming soon? i mean damn i havent even had a DX10 compliant PC yet haha!

    also.. quads are a bit more expensive.. i wanna stay at or around 1000 bux, the most im willing to spend is 1200 bux..
     
    Last edited: Dec 3, 2008
  24. wolf

    wolf Performance Enthusiast

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    yeah i always like future proofing moves, just because most games use 1-2 cores now, doesnt mean they wont use more later :)
     
  25. Jeff574 New Member

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    what do you think of the amd 9950 black edition ?? there quad core and quite a bit cheaper, how do they hold up against the intel performance wise?
     

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