1. Welcome to TechPowerUp Forums, Guest! Please check out our forum guidelines for info related to our community.

PCI-e x16 speeds

Discussion in 'Graphics Cards' started by Snipe343, Oct 9, 2007.

  1. Snipe343

    Snipe343

    Joined:
    Jul 31, 2007
    Messages:
    1,002 (0.38/day)
    Thanks Received:
    34
    whats benifet from runningat x16 than x8 i have mine in the 8x slot because the case is not in line with the mobo all the way
     
  2. kwchang007

    kwchang007 New Member

    Joined:
    Jan 27, 2007
    Messages:
    3,979 (1.40/day)
    Thanks Received:
    185
    Location:
    Severn, MD, USA.
    What the case isn't in line with the mobo? Well depends on the card....for a 8600..probably little to no difference.
     
  3. ccleorina

    ccleorina New Member

    Joined:
    Mar 9, 2007
    Messages:
    195 (0.07/day)
    Thanks Received:
    10
    Location:
    Overclocking Hell
    2% or 3% difference from 16x to 8x
     
  4. Snipe343

    Snipe343

    Joined:
    Jul 31, 2007
    Messages:
    1,002 (0.38/day)
    Thanks Received:
    34
    ok i dont why but the 1st pci e slot is out of line with the slot on the case
     
  5. kwchang007

    kwchang007 New Member

    Joined:
    Jan 27, 2007
    Messages:
    3,979 (1.40/day)
    Thanks Received:
    185
    Location:
    Severn, MD, USA.
    Defected case, or improper install? Can you post some pics, I'd like to see this, lol. But if all else fails, try bending the metal out of your way or something.
     
  6. ccleorina

    ccleorina New Member

    Joined:
    Mar 9, 2007
    Messages:
    195 (0.07/day)
    Thanks Received:
    10
    Location:
    Overclocking Hell
    Post some pic... we like to see it...
     
  7. JrRacinFan

    JrRacinFan Served 5k and counting ...

    Joined:
    Mar 17, 2007
    Messages:
    19,414 (6.97/day)
    Thanks Received:
    4,483
    Location:
    Youngstown, OH
    Full ATX motherboard in a ATX case with only 6 expansion slot openings? Hmmmm .....
     
  8. Snipe343

    Snipe343

    Joined:
    Jul 31, 2007
    Messages:
    1,002 (0.38/day)
    Thanks Received:
    34
    dont have a camera right now ill try to post picks later, i hate the mobo anyway its terrible i would love another excuse to get rid of it
     
  9. AddSub

    AddSub

    Joined:
    Aug 9, 2006
    Messages:
    1,001 (0.33/day)
    Thanks Received:
    152
    Hmm, aren't differences only noticable in SLI/Crossfire setups (with AA/AF maxed) and not in single card ones?
     
  10. imperialreign

    imperialreign New Member

    Joined:
    Jul 19, 2007
    Messages:
    7,043 (2.64/day)
    Thanks Received:
    909
    Location:
    Sector ZZ₉ Plural Z Alpha
    a x8 slot is a bit slower than a x16 slot, so one might notice a FPS difference between the two, depending on other hardware.

    but, quite a few mobo's out there drop the x16 speeds to x8 in xFire or SLI, even without AA/AF set to max. There are also a mobo's that don't drop the bandwidth, either . . .
     
  11. Kursah

    Kursah

    Joined:
    Oct 15, 2006
    Messages:
    7,882 (2.68/day)
    Thanks Received:
    1,715
    Location:
    Missoula, MT, USA
    I think some higher end PCI-e cards may notice a bigger fall when going from x16 to x8 link speed. But most mid-range and lower end cards don't seem to use the full x16 bandwidth, so maybe 8x link is fine, but really what would the point be if there is no real change aside from messing around? You won't gain anything by dropping speed, and odds are you won't lose much, but I just don't see why you would want to run it at 8x all the time.

    Sure in some X-fire setups the second card will drop speed, take my P5B Deluxe, the first card runs at full x16, the second runs at a cut-at-the-knees 4x. But I'm not a fan of dual cards, but I can usually get one card, OC it, and make it run as fast as I need for my games. You should run some benches at 8x and 16x and see what the difference is! Maybe try each at 100Mhz PCI-e and 105/109Mhz PCI-e...I wonder if there is anything there worth looking at...probably not. Just a tired thought...and after that I'm off to bed.

    :toast:
     
  12. AddSub

    AddSub

    Joined:
    Aug 9, 2006
    Messages:
    1,001 (0.33/day)
    Thanks Received:
    152
    yeah, I believe that is the case.
     
  13. Kursah

    Kursah

    Joined:
    Oct 15, 2006
    Messages:
    7,882 (2.68/day)
    Thanks Received:
    1,715
    Location:
    Missoula, MT, USA
    Too bad there wasn't a way to measure how many of the x16 links current cards are using. I wonder if increasing PCI-e Bus speed to the USED serial links of the PCI-e bus could improve performance. I mean this is just in theory, and I'm at work so I can't test it w/my x1950pro, but what if the link speed is reduced to 8x and PCI-e is set to 109 or 115+ Mhz if there could be performance there.

    I know on newer NV chipsets and newer NV cards (8800's) that increasing the x16 PCI-e bus speed can improve performance...but if a lower multi, higher speed PEG/PCI-e link was established for let's say 8600's, 2600's, pro's/gt's and such if there could be some extracted extra performance...probably not but I will try when I get home in about 7 hours.

    If anyone else is interested in testing this theory that'd be cool, I won't assume it will hinder or help performance until I test it and see some results. It can't hurt to try and see what happens w/the general synthetic benches and see if there's anything there.

    Anyone interested in trying? I may be able to check back in a little while, depends on how busy I get.

    :toast:
     
  14. kwchang007

    kwchang007 New Member

    Joined:
    Jan 27, 2007
    Messages:
    3,979 (1.40/day)
    Thanks Received:
    185
    Location:
    Severn, MD, USA.
    Yeah, but same theory applies if this guy can't get his card all the way into the x16 slot and only makes contact with 8 lanes...how that happens I have no clue.
     
  15. imperialreign

    imperialreign New Member

    Joined:
    Jul 19, 2007
    Messages:
    7,043 (2.64/day)
    Thanks Received:
    909
    Location:
    Sector ZZ₉ Plural Z Alpha
    I'm willing to give it a go with my 1950 later when I have time, I know my card is defi a mid-range, but any possible attempt to get some extra juice out of it . . . I haven't really messed with the PCIe frequency setting in BIOS yet either.

    y'know . . . I didn't think you could fit an x16 card into an x8 slot . . . like how an x8 won't fit in an x1 . . . seems odd, IMO
     
  16. kwchang007

    kwchang007 New Member

    Joined:
    Jan 27, 2007
    Messages:
    3,979 (1.40/day)
    Thanks Received:
    185
    Location:
    Severn, MD, USA.
    Neither do I. He says it's a x16 slot, but since the case doesn't line up he doesn't get full contact :confused:. Extremely confusing imo.
     
  17. Darknova

    Darknova

    Joined:
    Nov 8, 2006
    Messages:
    5,037 (1.73/day)
    Thanks Received:
    535
    Location:
    Manchester, United Kingdom
    There was an article on Tom's Hardware about PCI Express Scaling (The link is now dead..seems like they removed the article). Anyway they used the 7 series nVidias and 1950 series ATi cards, and by taping off parts of the connector they found they could reduce the number of lanes. So they tested this, and nVidias were the worst for PCI-E scaling. At 8x most of them lost nearly 40% performance. Where as ATi's were hardly hit, it wasn't until they got to 4x that performance halved, by this stage the nVidia's were at something like 20%.
     
  18. Kursah

    Kursah

    Joined:
    Oct 15, 2006
    Messages:
    7,882 (2.68/day)
    Thanks Received:
    1,715
    Location:
    Missoula, MT, USA
    Yeah I remember that article, kinda fuzzy, but I do remember skimming over it. If I have some time I'm still gonna see what happens at 8x/109+MHz, probably, little to nothing, but it's worth a shot.

    :toast:
     
  19. AddSub

    AddSub

    Joined:
    Aug 9, 2006
    Messages:
    1,001 (0.33/day)
    Thanks Received:
    152
    Excellent. I would be really interested in your results.
     
  20. imperialreign

    imperialreign New Member

    Joined:
    Jul 19, 2007
    Messages:
    7,043 (2.64/day)
    Thanks Received:
    909
    Location:
    Sector ZZ₉ Plural Z Alpha
    played with the PCI-e frequency setting in BIOS some, not much, though, as it's getting late here. I'll mess with it some more tomorrow, as I'm interested in seeing how high that setting can go before I start getting errors.

    Anyhow, there does seem to be a performance gain for a x1950. I used 3m06 for testing purposes, and a minimum of 15 minutes of cool down to idle temps before each change/run. Tested at the stock clock speeds of 575/1390, with ATi Tray Tools 3D profile set to "Auto Balanced". 3m06 at defaults. All other PCIe settings in BIOS (labeled as Peg Root controls) were all left to auto.

    PCIe @ 100 (the most commonly *recommended* setting) = 4192 marks
    PCIe @ 105 = 4193 marks
    PCIe @ 110 = 4241 marks
    PCIe @ 120 = 4306 marks

    so, it does seem to help. Although, I want to test higher settings, and I also want to test having it set to [AUTO]. From there, I want to see how much of a difference it makes running the card 5% OC (the highest 100% stable I can manage :ohwell:), and if there is any change with tweaking the Peg controls (specifically, slot voltage and bandwidth).
     
    Mussels says thanks.
  21. Mussels

    Mussels Moderprator Staff Member

    Joined:
    Oct 6, 2004
    Messages:
    42,401 (11.53/day)
    Thanks Received:
    9,700
    Please test this some more and compile your results into a single post. Once you get some good results, i'll test out the most interesting choices (if you hit a wall, or one result is faster than the others) and we'll see how it compares % wise to an 8800GTX.
     
  22. Tommithy New Member

    Joined:
    Dec 21, 2006
    Messages:
    34 (0.01/day)
    Thanks Received:
    1

    That Tom's Hardware article is Here
     
  23. Tatty_One

    Tatty_One Senior Moderator Staff Member

    Joined:
    Jan 18, 2006
    Messages:
    16,769 (5.23/day)
    Thanks Received:
    2,557
    Location:
    Worcestershire, UK
    There is plenty enuff bandwidth available at 8x for an 8600.....you only get the minor slowdowns when you use up all the bandwidth......an 8600 is very unlikely to do that, damn in one test I read.....2 x 8800GTX's at 16 x 16 against the same at 8 x 8 (the 680 V 650 boards showdown) only showed 2-3FPS difference at very high res in most games.
     
  24. Tatty_One

    Tatty_One Senior Moderator Staff Member

    Joined:
    Jan 18, 2006
    Messages:
    16,769 (5.23/day)
    Thanks Received:
    2,557
    Location:
    Worcestershire, UK
    Is that not frequency your testing there as opposed to bandwidth? As in speed of port as opposed to size of port.
     
  25. kwchang007

    kwchang007 New Member

    Joined:
    Jan 27, 2007
    Messages:
    3,979 (1.40/day)
    Thanks Received:
    185
    Location:
    Severn, MD, USA.
    Well bandwidth is a factor of speed multiplied by width, isn't it?
     

Currently Active Users Viewing This Thread: 1 (0 members and 1 guest)

Share This Page