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PCIe x4 card in a x8 slot

Hi, I have a Gigabyte EP45-DS4 motherboard, it has the following PCIe slots:

1 x PCI Express x16 slot, running at x16
1 x PCI Express x16 slot, running at x8
(The PCIEx16 and PCIEx8 slots support ATI CrossFireX technology and conform to PCI Express 2.0 standard.)
1 x PCI Express x4 slot
3 x PCI Express x1 slot
1 x PCI slots

Now it doesn't say that the x4 slot is PCIe 2.0 standard.
I want to put in a SATA3 controller that requires a x4 v2.0 slot.
Can I put it in the x16 slot running at x8 to take advantage of the 2.0 compliance?

Or, if I have to use the x4 slot, how will the SATA controller react to a 1.0 compliant PCIe slot?
9 answers Last reply Best Answer
More about pcie card slot
  1. Or likewise, could I put a PCIe x1 card into the x16 slot?
  2. Yes. Lower PCIE "x" will always work in the higher x slots. x1 x4 x8 can be used in x16
  3. Best answer
    ^+1

    All of your PCIe slots are/use the PCIe 2.0 standard. You can put a PCIe x1 Sound Card in a x16 PCIe slot, and PCIe 2.0 is also compatible with PCIe 2.0 and 1.x cards; likewise PCIe 3.0 supports PCIe 3.0, 2.0 and 1.x.

    You can even put a x8 card into a x4 slot -- the cost is loss in potential bandwidth. Each PCIe 2.0 lane (x1) is ~500MB/s so x4 is 4*500MB/s = 2000MB/s.

    Just a thought here, other than some benchmarks, the real world difference between the SATA2 (ICH10R/6x SATA Ports) and a SATA3 even with an SSD is basically 'zero' -- most of the gains in SSD's is latency and 4KB Random R/W (OS and Applications) so the only real gains are copying data from one SSD to another SSD. Also, many SATA Cards are not bootbale so you must verify that your BIOS allows the resources -- otherwise those new SATA3 ports will be DATA ONLY.

    GA-EP45-DS4 - http://www.gigabyte.com/products/product-page.aspx?pid=2840#sp
    1 x PCI Express x16 slot, running at x16
    1 x PCI Express x16 slot, running at x8
    (The PCIEx16 and PCIEx8 slots support ATI CrossFireX technology and conform to PCI Express 2.0 standard.)
    1 x PCI Express x4 slot
    3 x PCI Express x1 slot
    1 x PCI slots
  4. Awesome thanks guys.. So what about game loading times, for eg, loading a map that is over a gb, would the available 560mbps sequential read be available through the PCIe port? the SATA2 port will limit it down to 250 or less..

    And does anyone happen to know if this motherboard will support booting off a PCIe SATA controller?
    (Gigabyte EP45-DS4 & Marvell 9128)
  5. Best answer selected by thomajar.
  6. The Marvell 9128 will yield ~370MB/s-390MB/s (latest drivers), ICH10R ~290MB/s-295MB/s. If you're adding an SSD for e.g. 'Steam' then the file sizes varies, and clearly (yes) will load faster from an SSD but the differences between the ICH10R vs Marvell 9128 vs SATA3 Card will be very close at best a few (1-4) seconds between the (3) SATA ports.

    I have games stored on both my SSD (X79/SATA3) and HDD the differences might be 5~15+ (Crysis) seconds depending on the games' level.
  7. OK, yeh I might not bother then. I put the SSD in today, and unfortunately already ordered a pcie card..
    I did some benchmarks though and was topping out at around 200MB/s (Vertex 4 SSD)

    I have already got 4 SATA2 HDD's in RAID0 and a DVD SATA drive running off the Intel controller, I don't know if this could be slowing it down?

    With the PCIe x1 speed of 5gbps, is this 2.5 each way? or the full 5 duplex?
  8. Each ICH10R SATA Port is not shared and each port has full bandwidth, but the Marvell 9128 shares x1 PCIe 2.0 or 500MB/s or up to 200MB/s~<250MB/s when shared.

    If a SATA3 SSD is connected to the Marvell then only use (1) drive to achieve ~370MB/s-390MB/s (latest drivers) on its primary SATA port.

    PCIe bus links are full-duplex.
  9. Cool, thanks, I will only be using the one SSD drive so will hopefully double the throughput :)
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