AMD's Quad FX: Technically Quad Core
by Anand Lal Shimpi on November 30, 2006 1:16 PM EST- Posted in
- CPUs
Imagine for a moment you're at the decision making table at AMD; you are at least a year away from introducing an updated micro-architecture to refresh your now aging K8 design and your chief competitor just introduced faster and cooler CPUs than anything in your lineup. To make matters worse, this very same competitor enjoys a manufacturing advantage and has also announced that it will begin the transition to quad-core even earlier than originally expected, starting at the end of 2006. The earliest you can even hope to release a quad-core CPU is the middle of 2007. What do you do?
AMD's first move made sense, and that was to dramatically reduce the pricing of its entire lineup to remain competitive. Most computer components are not things you can buy and sell off of emotions alone, and thus something that performs worse must cost less. Through the price drops AMD actually ended up with a fairly attractive dual core lineup, although our similarly aggressive pricing from Intel meant that the most attractive AMD CPUs were the cheapest ones.
But what was AMD to do about the quad-core race? Even though Intel would release its first quad-core CPUs this year, less than 1% of all shipments would feature four cores. It won't be until the end of 2007 before more than 5% of Intel's shipments are quad-core CPUs. But would the loss in mindshare be great enough if Intel already jumped ahead in the race to more cores?
Manufacturing a quad-core Athlon 64 or Opteron on AMD's current 90nm process simply isn't feasible; AMD would end up with a chip that is too big and too hot to sell, not to mention that it would put an even greater strain on AMD's manufacturing which is already running at capacity.
With the 90nm solution being not a very good one, there's always the "wait until 2007" option, which honestly seemed like a very good one to us. We just mentioned that Intel wasn't going to be shipping many of these quad-core CPUs and the majority of users, even enthusiasts who are traditionally early adopters, will stay away from quad-core until 2007 at the earliest to begin with.
Then there's the third option, the one AMD ended up taking; instead of building quad-core on 90nm or waiting until next year, around April/May of 2006 AMD decided that it had a better solution. AMD would compete in the quad-core race by the end of 2006 but with two dual core CPUs running in a desktop motherboard.
Of course dual-core, dual-socket is nothing new, as AMD has been offering that on Opteron platforms for quite a while now. But the difference is that this new platform would be designed for the enthusiast, meaning it would come equipped with a performance tuned (and tweakable) BIOS, tons of USB ports, support for SLI, etc... Most importantly, unlike an Opteron system, this dual socket desktop platform would run using regular unbuffered DDR2 memory.
Back then the platform was called 4x4, and honestly it was about as appealing as a pickup truck. The platform has since matured and thanks to a very impressive chipset from NVIDIA and aggressive pricing from AMD, what's now known as Quad FX may actually have some potential. Today we're here to find out if AMD's first four-core desktop platform is a viable competitor to Intel's Kentsfield, or simply an embarrassing knee-jerk reaction.
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Viditor - Thursday, November 30, 2006 - link
If they can...
The 680a chipset has a direct HT link to each MCP, the 680i obviously can't do that and must bridge through the SPP.
Now if only we could find a review that actually showed that...;)
Seriously, the one major benefit of Quad FX is that it can run 4 GPUs. While I appreciate all of the conjecture and speculation, it isn't really a test of the facts, is it?
defter - Friday, December 1, 2006 - link
<quote>Seriously, the one major benefit of Quad FX is that it can run 4 GPUs.</quote>How that's a benefit? You can have 8 GPUs in a same system (AMD or Intel based, it doesn't matter) with a couple of NVIDIA Quadro Plex 1000 Model II's if money isn't an issue:
http://www.nvidia.com/page/quadroplex_comparison_c...">http://www.nvidia.com/page/quadroplex_comparison_c...
JarredWalton - Friday, December 1, 2006 - link
Fact: Quad SLI (7950 GX2) works on 590 SLI and 680i.Fact: Quad SLI (8800 GTX) does not exist.
Until the second item changes, we only have the first to go on, which is that current quad SLI works - at least as much as it works anywhere - on both platforms. And the QSLI drivers are still largely broken - you can run benchmarks, but as soon as you start playing lots of games rather than just benching, problems crop up. Neverwinter Nights 2 for example doesn't even run properly with CrossFire or SLI, so let's not even worry about getting QSLI support for now.
JackPack - Thursday, November 30, 2006 - link
8800 GTX requies two slots, which means it won't fit in the 4x4 motherboard. Quad-SLI performance has already shown to be poor using two 7950 GX2 cards. Finally, how do you bridge four 8800 cards together?Viditor - Thursday, November 30, 2006 - link
Huh?
http://www.bit-tech.net/hardware/2006/11/08/nvidia...">Single slot 8800 GTX
This is only when using a single MCP, the 680a uses dual MCPs.
The 680i uses one MCP and one SPP.
By having 2 sets of bridges (one bridge per MCP).
JarredWalton - Friday, December 1, 2006 - link
Quad SLI has problems whether or not you have dual MCPs. It's driver and software related - basically the drivers don't do AFR on a lot of titles and so you end up with lower than 7900 GTX SLI performance.As for two slots, they're talking the width of the cards. They only plug into one slot, but they fill the adjacent slot. Quad 8800 GTX would require eight expansion slots right now. Given that Vista 8800 drivers aren't even out yet, I think NVIDIA has other things to do before they worry about moving beyond SLI'ed 8800 cards.
PrinceGaz - Thursday, November 30, 2006 - link
I suppose you could replace the HSF with something smaller which would fit in a single-slot, which would have to mean water-cooling.Quad-SLI performance (or lack of) is probably a driver-issue.
Don't 8800 cards have two SLI sockets therefore allowing you to chain together as many as you like (in theory)?
casket - Thursday, November 30, 2006 - link
It appears with win-xp sp2... this quad fx stinks. How about Win 2003 or Vista Ultimate? It might change things drastically.Neosis - Thursday, November 30, 2006 - link
I don't think the problems in the benchmarks are not an opperating system issue. Two processors having totally four cores are not the same as a processor having the same number of cores. Additional latencies will slow down the performance.Viditor - Thursday, November 30, 2006 - link
Actually, they probably are...Windows XP is not NUMA aware, while Vista is.
In this case there is no difference...the Kentsfield has exactly the same latency as a 2 socket dual core because the 2 dual cores on-board don't talk directly with each other.