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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.
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