pci-express interview questions
Top pci-express frequently asked interview questions
I was tinkering with my PC yesterday and now I'm wondering about these things.
Not that it really matters to me, I'm just curious.
Example below:
Source: (StackOverflow)
My question is fairly simple. Can a x4 physical (mechanical component) fit in a x16 PCIe, which is at x4 mode?
Source: (StackOverflow)
If I add a SATA 6 Gbit/s PCI Express card to my motherboard, will I get similar speed to native SATA ports built into the motherboard? I ask because I have a SATA 6 Gbit/s SSD and my motherboard supports only SATA 3 Gbit/s.
Source: (StackOverflow)
I'm looking at building a system that supports VT-d so I can pass through a high powered loud video card to a Xen/KVM/whatever VM (host will be Linux based). However, when I'm not using the VM I want to turn the video card off so its fan does not run. The card will not be used when the VM isn't running.
Anyone know if this is possible? The PCI-Express hot-plug specification allows cutting power to specific slots but I have never heard of anyone doing it with a video card and my searches for information have turned up nothing.
Source: (StackOverflow)
For my computer I am thinking to purchase one of these, which needs two SATA connectors, but I am concerned about not having enough SATA connections on my motherboard (I already have two HDDs and an SSD using the current SATA ports).
So I was thinking to purchase one of these PCI-express cards to get an extra SATA port (I need the 20-pin internal USB 3.0 port too for the Syba Drive Bay). But this pci card touts a PeSATA adapter, not a SATA port. From the photo it looks a lot like a regular SATA connector, but I can't find information on PeSATA.
Is PeSATA the same as SATA?
Source: (StackOverflow)
Perhaps I may be overlooking some aspect that is an important cause as to why these don't exist, but I feel that having RAM expansions through PCIe would be perfectly feasible. I know that a lot of operating systems use virtual memory and store some lower priority items on hard disks, but considering the lower speeds I feel that we could use some bonus not-quite-as-fast memory.
6Gb/s SATA ~= 800MB/s
PCIe 2.0 = 500MB/s per lane. 16 Lane ~= 8GB/s
Sure, 8GB/s isn't as fast as actual RAM, but it's 10x the speed of SATA. Why not have a PCIe board with a couple of RAM slots for use with the old RAM that you just replaced with that recent upgrade? PCIe has the benefit of being on almost every motherboard out there. One 'adapter' PCIe RAM Expansion Board would be (supposedly) compatible most PCs.
What am I missing since this hasn't been done yet?
Source: (StackOverflow)
I'm researching dual QSFP 40GBit network cards for a work project and have a few questions regarding PCIe 3.0's theoretical max bandwidth.
I'm currently looking at a dual QSFP PCIe 3.0 x8 card on CDW (Mellanox MCX314A-BCBT), but I don't think PCIe x8 would provide enough bandwidth for both 40Gbit links at 100% utilization.
Wikipedia states that PCIe 3.0 has a theoretical max bandwidth of 985MB/s per lane. Thus, by my calculations, PCIe 3.0 x8 would yield a max bandwidth of 7880MB/s. If this is true, the card would saturate the PCIe connection if both links are at 100% utilization.
Here are my specific questions:
What is the max bandwidth that a dual QSFP 40Gbit network card can output?
What is the max bandwidth that a PCIe 8x can handle before saturation?
Is there an easy way to calculate this?
Source: (StackOverflow)
I am building a file server my plan is the have the Operating system on one raid partition and the data storage on another partition.
I currently have 5 x 3GB IDE drives that i would like to put the operating system on theses drives are old but that doesnt matter to me at the moment i have a ton of them so for this raid partition i would probably want to be able to pull out dead a drive and rebuild the array.
My file partition is going to consist of 4 x 1.5TB SATA drives I would like the maximum storage with some redundancy.
Any suggestions to which Raid level i should use would be greatly appreciated and if you could also suggest a PCI or PCI-e raid controller to handle theses arrays.
Thanks in Advance,
Zen_Silence
Source: (StackOverflow)
I have a mini itx pc with only one pci-e x16 slot. There is another old style pci slot.
I don't care that much about graphics bandwidth and I'd like to add USB 3.0 support. It's a waste to be using 16 lanes of pci bandwidth for a graphics card I hardly use, and I've found some convenient front panel usb 3.0 cards that only need a 1x pci slot.
I've seen products that allow people to split the pci slots into their seperate channels. They appear to be purely mechanical devices.
I'd like some advice regarding how to get my single x16 slot to support a small graphics card plus a 1x or maybe 4x usb 3.0 card. Some front panel usb 3.0 cards take up very little space at the actual pci-e slot as the cards main board is in the front panel unit.
What would be perfect would be a low profile graphics card that had a pci riser onboard but I doubt this exists and would probably be over priced if it did.
A graphics card that didn't take up the whole x16 slot might be acceptable if it's possible to use the last channel at the same time for a 1x riser or something, don't know if that's allowed.
I will consider acts of physical force on the hardware if deemed necessary to "persuade" it to comply. For example I've seem example of people putting x16 graphics cards into x1 slots just by opening the back of the slot and they still worked.
Source: (StackOverflow)
I am looking into a situation where there are multiple, identical (National Instruments) PCIe DAQ modules in a PCI/PCIe chassis, connected via either a single or dual chassis controller. In the worst case scenario there can be 8 identical modules on the bus.
I have been led to believe that PCI enumeration is non-deterministic - i.e. that there is no guarantee that, boot to boot, the PCI bus will be enumerated in the same order. Is this true?
Does this also imply that PCI(e) bus/device/function values can change, boot to boot, even if the physical hardware layout does not?
In short, I understand that initial PCI enumeration is done by the BIOS, and that the boot OS (RHEL 6, in my case) uses this enumerated list to service identified hardware. Does this list always contain the found devices in the same order or not?
This is a hint in Red Hat Bugzilla that implies that BIOS ordering is always the same.
Please note that I am not (yet) talking about the order in which the OS handles the devices (e.g. for, in Linux, determining the /dev/ name order).
Thanks!
Source: (StackOverflow)
I have this motherboard with 2 PCI-E Graphics cards, apparently only one of them is actually x16 what ever that means.
http://www.gigabyte.com/products/product-page.aspx?pid=2625#ov
If I put the same graphics card in each slot, will I get a performance boost in games? (I belive SLI is not supported on this board, although the card I have do support it)
This is the video card I have and I was going to get another one.
http://www.gigabyte.eu/products/product-page.aspx?pid=2804#ov
And can someone please explain the difference between "PCI-E 16 x4" and "PCI-E 16 x16"?
Thanks heaps.
UPDATE:
Performance Mark Tests showed 10FPS in Complex 3D tests on the x4 Slot and 57+ FPS on the x16 slot.
Nothing else really differed.
Source: (StackOverflow)
The Perpetrating PC...
- MB:MSI Z77A-GD65
- OS:Windows 7 Pro
- CPU:Intel Core i5-3570k Ivy Bridge
- Memory:16gig G.Skill Ripjaw
- PSU:Cooler Master Silent Pro 700w
- HD:1TB WD Cavier black
- Rosewill rc-300e PCI Express x1 serial card
- VGA:(2) Nvidia Quadro FX 3500 SLI
- Monitor:24" Samsung
This computer is used to send G-Code programs to a Horizontal CNC Milling machine through serial DNC. Up until last week everything was working fine with the Rosewill serial card in the above machine. All of a sudden on Friday of last week all communications between the Horizontal CNC and the computer stopped. I asked the user if any updates had come down or new software was installed. The user assured me that nothing changed between the last time it worked and it's failure.
Troubleshooting.
- Tried reinstalling the drivers (both with and without removing the driver first).
- Tried both the drivers on the CD that came with the Rosewill rc-300e card and the latest drivers online.
- Tried 3 different Rosewill rc-300e cards in all 5 PCIe slots (x1 and x16) on my MSI board.
- Tried reinstalling the OS on the PC.
- Tried 2 different Windows 7 computers both with Asrock Extreme 4 z77 motherboards and the Rosewill rc-300e serial cards. Neither worked.
- Tried connecting a different serial device (an engraving machine) to all 3 above computers (2 Asrock and 1 MSi) with the Rosewill rc-300e serial cards and all three worked fine. So it's not the ASrock or MSI PCs.
- I tried connecting the Horizontal to two old Windows XP Lenovo Thinkcenters with on-board serial. Those both worked fine talking to the Horizontal. So it's not the horizontal or its serial cable.
- So lastly I thought I'd try the Rosewill serial card in the Thinkcenter. That worked fine. So it's not the serial card.
Steps 6, 7 and 8 are what makes this whole thing weird. The only commonality that I can find is that it works with Windows XP but does not with Windows 7. BUT, it worked fine with Windows 7 prior to last Friday and absolutely nothing had changed on the PC (or any of the other Windows 7 PCs for that matter.)
Anyone have any ideas?
Source: (StackOverflow)
If I buy a PCI-E v2.0 graphics card (Nvidia Geforce GTX 275) will it work correctly and to the full potential with my PCI-E v1.0 motherboard (Asus P5B-Deluxe) ?
Source: (StackOverflow)
I'm trying to figure out whether my system supports PCI Express without opening up the box. lspci doesn't mention "Express" or "PCI-e" anywhere, but dmesg reports that a "PCI Express Hot Plug Controller Driver" is in use.
Source: (StackOverflow)