Odds & Ends: ECC & NVIDIA Surround Missing

One of the things we have been discussing with NVIDIA for this launch is ECC. As we just went over in our GF100 Recap, Fermi offers ECC support for its register file, L1 cache, L2 cache, and RAM. The latter is the most interesting, as under normal circumstances implementing ECC requires a wider bus and additional memory chips. The GTX 400 series will not be using ECC, but we went ahead and asked NVIDIA how ECC will work on Fermi products anyhow.

To put things in perspective, for PC DIMMs an ECC DIMM will be 9 chips per channel (9 bits per byte) hooked up to a 72bit bus instead of 8 chips on a 64bit bus. However NVIDIA doesn’t have the ability or the desire to add even more RAM channels to their products, not to mention 8 doesn’t divide cleanly in to 10/12 memory channels. So how do they implement ECC?

The short answer is that when NVIDIA wants to enable ECC they can just allocate RAM for the storage of ECC data. When ECC is enabled the available RAM will be reduced by 1/8th (to account for the 9th ECC bit) and then ECC data will be distributed among the RAM using that reserved space. This allows NVIDIA to implement ECC without the need for additional memory channels, at the cost of some RAM and some performance.

On the technical side, despite this difference in implementation NVIDIA tells us that they’re still using standard Single Error Correction / Double Error Detection (SECDED) algorithms, so data reliability is the same as in a traditional implementation. Furthermore NVIDIA tells us that the performance hit isn’t a straight-up 12.5% reduction in effective memory bandwidth, rather they have ways to minimize the performance hit. This is their “secret sauce” as they call it, and it’s something that they don’t intend to discuss at in detail at this time.

Shifting gears to the consumer side, back in January NVIDIA was showing off their Eyefinity-like solutions 3DVision Surround and NVIDIA Surround on the CES showfloor. At the time we were told that the feature would launch with what is now the GTX 400 series, but as with everything else related to Fermi, it’s late.

Neither 3DVision Surround nor NVIDIA surround are available in the drivers sampled to us for this review. NVIDIA tells us that these features will be available in their release 256 drivers due in April. There hasn’t been any guidance on when in April these drivers will be released, so at this point it’s anyone’s guess whether they’ll arrive in time for the GTX 400 series retail launch.

The GF100 Recap Tessellation & PhysX
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  • Ryan Smith - Saturday, March 27, 2010 - link

    Yes, we did. We were running really close to the limits of our 850W Corsair unit. We measured the 480SLI at 900W, which after some power efficiency math comes out to around 750-800W actual load. At that load there's less extra space than we'd like to have.

    Just to add to that, we had originally been looking for a larger PSU after talking about PSU requirements with an NVNDIA partner, as the timing of this required we secure a new PSU before the cards arrived. So Antec had already shipped us their 1200W PSU before we could test the 850W, and we're glad since we would have been cutting it so close.
    Reply
  • bigboxes - Sunday, March 28, 2010 - link

    Appreciate the reply. Reply
  • GullLars - Saturday, March 27, 2010 - link

    OK, so 480 generally beats 5870, and 470 generally beats 5850, but at higher prices, temperatures, wattage, and noise levels. What about 5970?

    As far as i can tell, the 5970 beat or came even with 480 in all tests, draws less power, runs cooler, and makes less noise. The price isn't that much more either.

    It seems more fair to me to compare 480 with 5970 as both are the fastest single-card (as in PCIe slot) sollutions and are close in price and wattage.

    I would also like to see what framerate FPS games come in at with gamer settings (1680x1050 and 1920x1200 resolutions), and if average is higher than game cutoff or tickrate, what is the minimum FPS, and how much can you bump eyecandy before avg drops below cutoff/tickrate or minimum drops below acceptable (30).

    The reason for gamers sacraficing visuals to get high FPS can be summarized to game flow and latency. If FPS is below game tickrate, you get latency. For many games the tickrate is around 100 (100 updates in the game engine pr second). At 100 FPS you have 10ms latency between frames, if it drops to 50 you have 20 ms, and at 25 you have 40 ms. Lower than 25-30 FPS will obviously also result in virtually unplayable performance since aiming will becoming hard, so added latency from FPS below this becomes moot. If you are playing multiplayer games, this is added to the network latency. As most gamers know, latency below 30ms is generally desired, and above 50ms starts to matter, and above 100ms is very noticable. If you are on a bad connection (or have a bad connection to the server), 20-30ms added latency starts to matter even if it isn't visually notable.
    Reply
  • bigboxes - Saturday, March 27, 2010 - link

    Anyone else getting that message? I finally had to turn off the 'attack site' option in FF. It wasn't doing this last night. It's not doing it all over AT, just on the GTX 480 article. Reply
  • GullLars - Saturday, March 27, 2010 - link

    Here too, it listed among others googleanalytics.com as a hostile site.

    It was probebly because NVidia wasn't happy with the review XD
    (just joking ofc)
    Reply
  • chrisinedmonton - Saturday, March 27, 2010 - link

    Great article. Here's a small suggestion; temperature graphs should be normalised to room temperature rather than to 0C. Reply
  • GourdFreeMan - Sunday, March 28, 2010 - link

    I agree. Temperature graphs should either be normalized to the ambient environment or absolute zero; any other choice of basis is completely arbitrary. Reply
  • Ahmed0 - Saturday, March 27, 2010 - link

    Uh oh, my browser just got a heartwarming warning when I clicked on this article, the warning said that it might infect my computer badly and that I should definitely run home faster than my legs can carry.


    So, whats up with that?
    Reply
  • Lifted - Saturday, March 27, 2010 - link

    I just got that too. Had to disable the feature in Firefox. Reply
  • NJoy - Saturday, March 27, 2010 - link

    well, Charlie was semi-accurate, but quite right =))What a hot chick... I mean, literately hot. Way too hot Reply

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