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More on BTX Motherboards
venger writes "Anandtech has an article on the new standard of cases and motherboards that is soon to be released. Looks like they are trying to cater for the increase in heat devices are now producing while keeping the noise levels down!" We mentioned BTX earlier.
I think I can safely assume that PCI Express has a bandwith that is much faster than that of AGP can ever have
The AGP 8x spec has a max bandwidth of 2.1GB/s, while PCI Express x16 has a bandwidth of 8 GB/s. It might be theoretically possible to create a AGP 32x spec (although I doubt it), but the obvious question would be why?
. But isn't the point of AGP that it allows you to set an arperture and use some of the system RAM as an extension of the memory on the graphics card?
No, the point of AGP was to give a single slot increased bandwidth that's needed for modern graphics cards. PCI just isn't fast enough. Intel wrote into the spec that you could get away with sharing main memory as video memory in order to reduce system costs, but in practice nobody does this except for the absolute bottom tier PCs. The performance hit is huge.
wont AGP still be better?
No. Although it's questionable that PCI-X will really provide any speed increases. AGP 8x has a negligible speed improvement over AGP 2x, and quadrupling the bandwidth again isn't likely to do much either. I'm pretty sure PCI-X can still do the main memory-as-video memory trick, but there's really no need or desire to do so. If your card doesn't have enough memory to hold the textures then you're going to have a massive speed hit when you need to get them from memory. In practice this speed hit is so severe that the amount of bandwidth has relatively little impact on things -- it's the latency that kills.
Solution:
1) Go to an Anandtech review
2) Click on "Print this article" link at bottom of page
3) Read the review in one page with no ads
It helps to have a decent browser (ala Firebird), as the "print article" link is a java pop-up window. You can force it to a new tab with the correct settings.
pci-x != pci express
pci-x has been around a while
A few things.
First, heat rises. Which means that you can use convection.
Second, I think they are deliberately making it incompatable with ATX because they want to make sure that you put a BTX motherboard in a proper case. To be quiet, they are going to have to run with as little cooling as possible for a given configuration, thus little things like having the vent holes done up properly are going to count.
Third, you are more likely to have short PCI cards than room in front of the CPU for hard drives. Sure the video cards are still huge, but most everything else is pretty small.
Fourth, the main push is for tiny motherboards, not large motherboards. The full size format is there mostly so that there will be a large enough BTX audience to make a difference.
It should be interesting to see how this plays out. From the looks of it, it doesn't look to be too dual-CPU friendly. There's not much that's strictly wrong with the ATX standard right now (There was major Baby-AT compatability problems and random headaches back in the day) so there's not as much of an incentive to switch form factors. The enthusiasts, who can be counted upon to upgrade regularly and choose whatever brightly colored, feature-filled motherboard is available, aren't going to find much of an audience. It doesn't look too friendly for 1 and 2 U rackmount systems.
But it might do some good work on replacing the LPX form factor and many of the myriad not-particularly-standard tiny ATX standards.
Of course, those who have been watching the computer market for a long time know that the case market has moved towards small cases, and then back to tower cases, several times so far. Apple didn't revolutionize the computing market with the iMac, the case has been part of your positioning ever since the who-knows-how-many colored Cray supercomputers. People loved C64-style keyboard-is-the-computer cases for a span of time. People wanted thin, sexy cases before almost everybody switched to tower cases that could be hidden under the desk. Beige Toasters like the early Macs and the PS/2 mod 25 were popular for a time, but there was a span where nobody made them.
Gentoo Sucks
Actually, AGP was really developed to solve a problem that went away on its own; 2-D graphics.
The big bottleneck on PC graphics for years and years was the bus speed. When you are doing 2-D graphics, in essence you have to copy your graphic data out, frame by frame, to the display memory. The system bus was always the bottleneck here. To animate a 320x200 screen at 30 frames per second, you have to push out about 2 megabytes per second. 640x480 is four times that; 1024x768 takes about 24 megs per second. These are all in 1-byte pixels, or 256 colors; to do this in 32-bit color you'd have to push 4 times as much again, or about 95 megabytes/second for that 1024x768 screen. The numbers go up really, really fast as you get to higher resolutions.
So the big thing with PC graphics, for a long time, was increasing the bus speed. The original 8-bit ISA bus can push 4.77 megabytes per second, which wasn't able to animate even 320x200 because that same bus also had to do all memory access and other I/O. The 16-bit ISA slots could do 16 megabytes/second (8mhz x 16 bits.): with the system overhead, you could definitely do 320x200, and you could probably do 640x400 with very, very clever programming, but it would be iffy.
It was about then that graphics really started getting important, and VESA Local Bus was invented to extend the spec; I believe that was a 32-bit bus running at 33, 40, or 50 megahertz, depending on the CPU it was attached to. (VLB was a very simple design that was "close" to the processor electrically, and ran off its front-side bus.) As per the calculations above, you could put out a lot of data to a VLBus card, enough to render a 1024x768 screen. PCI was invented at about the same time, and while it wasn't as fast as a 50Mhz VLB card, it was flexible enough that it eventually supplanted VLBus, which died quietly.
PCI can do 133 megabytes/second (33 mhz x 32 bits wide). so 1024x768 is about the hard limit there. I'm not sure if they were pulling main memory off onto its own bus yet (as they do with modern machines), so if the video card was still competing with main memory, true 1024x768 at 30 frames per second would have been very difficult. With a modern machine, it would be no problem, as long as the computer wasn't trying to hit any of the other PCI cards too hard.
Well, Intel could see the writing on the wall, and came up with AGP. AGP 1x runs at twice the speed of PCI and hence has twice the bandwidth; the later 2x, 4x, and 8x specs doubled the speed each time. An AGP8x board can shovel out about 2.1 gigabytes/second, which is enough to comfortably animate 1600x1200 at several hundred frames per second. (perhaps as much as a thousand with, again, clever programming.)
But while they were busily solving the bandwidth problem, it went away. All this speed isn't really being used anymore. Over the last few years, PCs have switched away from using 2-D graphics to using 3-D graphics for most games. And 3-D is represented very differently; it is sent to the graphics card as a series of textures and triangles, and rendered on the graphic card itself. What this means is that the necessary bus speed DROPPED by a great deal. You can run most modern games very nicely on an NVidia PCI card. As long as your textures fit in the RAM of the card, you probably won't even be able to tell it's PCI instead of AGP.
The other thing that AGP promised was texturing out of main RAM, but the AGP bus (not to mention the RAM in the average PC) is nowhere near fast enough to do that.
So it's that last thing that PCI Express may be good for. Assuming that it can still do texturing out of main RAM, it's possible that that idea might finally start working. But that's pretty much the only reason it would be very interesting, at the moment; in a mostly-3d world, graphics are fine on the regular old PCI bus.
But I bet the demo coders will love it.
Try this case out for size -> http://www.procooling.com/reviews/html/antec_sonat a_case_review.php . It's gotten rave reviews for being super quiet and cool. I just assembled mine earlier this evening, and you can barely tell it is on unless you look at it closely. The 120mm fans in front and in back are dead quiet, plus the power supply is designed to be quiet, also. I even purchased a Zalman 6000CU CPU fan with speed control to keep the noise down.
Oh, the case also has rubber
grommets on the hard drive mount points to deaden any noise the HD's may make. And the fans are mounted with rubber-like screws to deaden any noise that may be caused by the fan vibrating against the case.
I can't afford a sig!