{ "numMessagesInTopic": 9, "nextInTime": 1917, "senderId": "uR45PzL4IbzA017e2LrLMBf68VJYKDSVt1wPktyShafINg8OPsaW8Zi6FqL-5O9PN7fx1OCWPjWB6ss1Lx5Dr79GK0Te8qbB9Uf3vnFl", "systemMessage": false, "subject": "Re: 4 PCIe X16 board :", "from": ""educationk12" <educationk12@...>", "authorName": "educationk12", "msgSnippet": "The previous posts with concerns as to whether XP could handle four graphic cards with a total of 1GB (256mb x 4 or even 512MB x 4) of graphics memory or", "msgId": 1916, "profile": "educationk12", "topicId": 1769, "spamInfo": { "reason": "6", "isSpam": false }, "replyTo": "LIST", "userId": 247597564, "messageBody": "
--- In IBM_T2X_LCD@yahoogroups.com, "fluppeteer" <yahoo@...> wrote:
\n>
\n> --- In IBM_T2X_LCD@yahoogroups.com, "coolwhs" <jjsmithdds@> wrote:
\n> >
\n> > Only problem is that this board is electrically a 8x, 8x, 4x, 8x,
\n> > which could cause problems with the video cards used.
\n>
\n> To clarify, in case anyone picks up on this and gets confused
\n> (I'm not suggesting that coolwhs is - no offence intended):
\n>
\n> This board has 16-lane physical connectors, which means each slot
\n> must be able to provide the full 75W of power, and therefore it
\n> can run any 16-lane card plugged into it. However, only some of
\n> the PCI Express data lanes are wired up (hence the 8x or 4x
\n> rather than 16x) description. PCI Express requires that the cards
\n> negotiate the number of lanes available to them and operate
\n> accordingly, so any 16-lane card will work in one of these slots,
\n> but (since it has fewer lanes over which to transfer data) with
\n> 1/2 (for an 8-lane slot) or 1/4 (for a 4-lane slot) the transfer
\n> rate to the computer of a genuine 16-lane connection.
\n>
\n> If what you're doing doesn't require the transfer of much data
\n> across the bus, this might not bother you, and you can still use
\n> "normal" graphics cards (as opposed to the single-lane cards
\n> in the Quadro nvs and Matrox series that require little enough
\n> power to run in a genuine single-lane PCI-e slot). If you *are*
\n> transferring a lot of data from the computer to the card, you
\n> might want to steer clear. Bear in mind that screen update of
\n> a T221 can involve transferring 36MB of frame buffer back and
\n> forth (especially noticable when the XP shutdown dialogue is
\n> on screen and the desktop fades to grey), so the threshold is
\n> different from "normal" monitors - but you get the same effect
\n> from a 2048x1536 screen on a PCI graphics card; it's not
\n> directly something special about the T221. How much you'd
\n> notice it if you're only updating the screen at 25Hz depends
\n> on what you're doing. :-)
\n>
\n> So, the only "problem" with the video cards is that they might
\n> not behave as quickly as if put in genuine 16-lane slots. They
\n> should, if they follow the PCI-e spec, still work - although
\n> it's always possible that features like Turbocache might not
\n> like being throttled. (I've never tried it, but it's probably
\n> not a good idea to put a card that depends on sharing memory
\n> over the PCI-e bus into a narrow slot).
\n>
\n> Hope that helps someone.
\n>
\n> --
\n> Fluppeteer
\n>