Slashdot Mirror
NVIDIA Responds To GTX 970 Memory Bug
Vigile writes Over the past week or so, owners of the GeForce GTX 970 have found several instances where the GPU was unable or unwilling to address memory capacities over 3.5GB despite having 4GB of on-board frame buffer. Specific benchmarks were written to demonstrate the issue and users even found ways to configure games to utilize more than 3.5GB of memory using DSR and high levels of MSAA. While the GTX 980 can access 4GB of its memory, the GTX 970 appeared to be less likely to do so and would see a dramatic performance hit when it did. NVIDIA responded today saying that the GTX 970 has "fewer crossbar resources to the memory system" as a result of disabled groups of cores called SMMs. NVIDIA states that "to optimally manage memory traffic in this configuration, we segment graphics memory into a 3.5GB section and a 0.5GB section" and that the GPU has "higher priority" to the larger pool. The question that remains is should this affect gamers' view of the GTX 970? If performance metrics already take the different memory configuration into account, then I don't see the GTX 970 declining in popularity.
You're describing 'TurboCache' (a marketing name if ever there was one).
It wasn't a secret, it was only on very low end cards, and ATI was already doing the same with 'HyperMemory'. Intel, for their part, was exclusively using system RAM at the time (and largely still is).
So what graphics *have* you been buying for the last decade?
How can I believe you when you tell me what I don't want to hear?
I'm just going to come out and say that to advertise the card with 4GB, but then disable any amount of it, is false advertising.
i agree. however in this case, all 4 Gigabytes are accessible, they simply aren't accessible at the same speed. the final 500MB is "slow" to access but it's still there and you can still access it.
Anons need not reply. Questions end with a question mark.
VRAM has nothing to do with system RAM. VRAM is special memory used by the dGPU, and only the dGPU, for storing framebuffers, textures, models, and other data needed to draw a 3D scene. It's faster than system RAM (GDDR5 is typical, vs DDR3 for regular RAM), and positioning it closer to the GPU reduces latency due to the speed of light (which travels only 10 cm in a single 3 GHz cycle). So the 32- or 64-bitness of the OS and apps has nothing to do with the video card's ability to access 4GB or more of VRAM.
In particular, the 970 GTX has a 256-bit memory bus. The speed constraint of having to retrieve data from VRAM one 32-bit (float) or 64-bit (double) "chunk" at a time became a bottleneck long before the inability to address that VRAM as a flat memory space. So mid- and high-end video cards are designed to retrieve multiple "chunks" of data from VRAM simultaneously. You have to drop all the way down to the GT 730 before you get to video cards using a 64-bit memory bus.
Silly person!
Use UMBPCI instead of EMM386, and use CTMOUSE for the mouse driver.
(assuming your modern system still knows how to play right in real mode anyway. Many modern chipsets have problems with ISA style DMAs, which makes using the hardware UMBs free with UMBPCI can have unpredictable results. For such systems, you are stuck with EMM386 doing protected mode memory reassignments, and gobbling down a big chunk of conventional. Blech.)
Really, there are much better memory managers that came about since the DOS days (FreeDOS is still a living project for devices that simply must run DOS. Industrial vinyl cutters and the like come to mind), and you can reasonably get over 568k conventional free with little hassle.