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Quick PC question if anyone knows

Discussion in 'General Open/Public Discussion' started by Doomhawk, 16 Mar 2010.


  1. Doomhawk

    Doomhawk Council of Elders<BR>UberPigeon Elder DragonWolf

    I believe it is possible to run a pcie-x1 card in the longer pcie-x16 slots right ?

    Thinking about buying a new vid card for my gaming system in a couple months and if its a doublestacked card its going to cover the one pcie-x1 slot im using for my soundcard.

    I feel like a nub for not knowing this for positive lol, but i figure its better to ask rather then melt my system :p
     
  2. symen

    symen DragonWolf

    Theoretically, this should work fine. When you turn your computer on, all of your PCI Express devices negotiate with the bus switch to determine the maximum number of serial lanes that their links can consist of. In practice, though, your BIOS may not take into account the possibility of a device other than a video card being plugged into the x16 slots (Dell, at least, does this), so there is a chance it won't work. Check with your motherboard manufacturer, or just try it -- it won't damage anything, the absolute worst case is that the system just won't POST with the card in there.

    Even if it doesn't work, PCI is a somewhat better choice for sound cards, anyway -- just get a PCI sound card if you have to. As PCI Express is a serial bus rather than a parallel one, its latency is somewhat higher than PCI, even though raw throughput is higher. This is great for video, which is constantly being refreshed (your screen is always displaying something), but suboptimal for sound, which is very bursty and intermittent on the bus.
     
  3. Doomhawk

    Doomhawk Council of Elders<BR>UberPigeon Elder DragonWolf

    Cool, thanks Symen. I just wanted to make sure i wouldnt fry something if I did try it. Pretty sure my mobo would have no issues with it. It was one of the last high end P35 boards.

    http://www.newegg.com/Product/Product.aspx?Item=N82E16813136037

    Although one question I did have still, I think alot of boards split your x16 bus into 8x 8x if you run 2 vid cards ? If you install a 1x sound card into one of those slots, will it effect that x16 vid card bus on those boards? Pretty sure that wouldnt be an issue with mine since I think its locked at 16x regardless of whats in the other 2.

    Also I bought the pci-e version of the sound card I have (x-fi titanium fatality pro) because I saw alot of post with people saying pci boards could pickup interference through the bus somehow. No idea if thats true or not, but in every system ive built ive always had backround noise in my sound so thought id try one out. Creatives drivers suck of course, but ive been really happy with it using an optical line and dts output.
     
  4. symen

    symen DragonWolf

    I'm not sure on this one. It is possible that there are only sixteen lanes available for those two slots, so this could happen. It is equally possible that there are only sixteen lanes available for video, so a sound card using one lane would have no effect on your video speed. This would depend on your motherboard, or perhaps on your northbridge chipset.

    I would be very surprised if this were the case. Your sound card is fundamentally a very simple device, the purpose of which is to convert a digital signal into an analog voltage on a wire which goes to a speaker. Let's say you are listening to a CD; the data arrives at the sound card as a pair of 16-bit numbers, ranging in value from 0 to 65535, 44,100 times a second. On the PCI bus, this is represented as a voltage of either 0 volts (for binary 0) or 3.3 volts (for binary 1) on 32 'address/data' connections, depending on the value. A lot of imprecision is tolerated, though. A voltage of up to 1 volt or so will be read as a binary 0, and a voltage as low as 2 volts or so will be read as a binary 1; not that either of these extreme cases could ever happen, as the two values are derived internally by opening or closing gates and electrically connecting the data line either to the power supply's 3.3-volt rail or to ground. Digital devices, as a rule, are not particularly susceptible to electronic interference.

    The binary signal representing the music on your CD is sent directly to the audio chipset after it arrives from the bus. This chipset is responsible for summing and mixing of streams, which it does digitally. This is very straightforward, actually: Let's say your software mixer's volume is set to 75% of maximum -- the chipset just multiplies the samples by 0.75 and passes them on to the digital to analog converter.

    The digital to analog converter is another very simple device; it simply converts a numeric value to a voltage. Your 3.3 volt and -3.3 volt power connections are used here. 0 is translated to -3.3 volts, 65535 is translated to 3.3 volts, and various appropriate resistances are applied to arrive at the appropriate voltages in between. The voltage is applied directly to the jack which your speakers are connected to. Now, we have an analog connection, where interference is possible. However, for audible interference to be induced, a signal must exist which is oscillating in the range of the frequency response of your speakers (for average computer speakers, this is about 100 Hz to 13 kHz. The PCI bus lines oscillate at 33 mHz, far beyond the range of either the frequency response of your speakers or your hearing. Not to mention, (doing a quick, off-the-cuff calculation here), if we assume that the circuit boards in your computer have a minimum resistance of 50,000 ohms (in practice, it will be much higher), then an oscillation in the range of 12 volts would be required to induce the 0.001 volt change on the audio lines required to be audible (and that would be quite subtle). The only signal inside your computer that is even vaguely close to this is the 12-volt line, but that is non-oscillating (except for an allowed 50 mV of ripple in the 10 to 20 mHz range) direct current, so any voltage induced from it would not be audible.

    Of course, this only applies to the old 1/8 inch analog output. Using the optical and DTS outputs, it's digital all the way, and induced noise is fantastically unlikely regardless of the bus the card is plugged into.

    Short answer -- if you're getting noise induced, it's most likely happening on the wires trailing out of the back of your computer.
     
  5. Sentrosi

    Sentrosi Protocol Officer Officer

    Officer
    And it should be ok to hook up a Wireless PCI NIC card to the PCI x16 slot, right?
     

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