AMD's Quad FX: Technically Quad Core
by Anand Lal Shimpi on November 30, 2006 1:16 PM EST- Posted in
- CPUs
Power Consumption
Power consumption of a Quad FX system is simply unreal for a desktop, as it should be because this is effectively a workstation platform with un-buffered memory. At idle our Quad FX test bed consumed nearly 400W, partially because we couldn't get Cool 'n Quiet running on the system, but also because the CPUs and motherboard simply draw an incredible amount of power. Update: We got Cool 'n Quiet working on the motherboard which reduced idle power significantly, down to within a few watts of the Kentsfield system. Load power was unchanged.
| CPU | Idle Power | Load Power | Performance per Watt (fps/watt) |
| AMD Athlon 64 FX-74 (3.0GHz x 4) | 217W | 456W | 17.7 |
| Intel Core 2 Extreme QX6700 (2.66GHz x 4) | 213W | 263W | 32.9 |
Looking at power consumption under full load, Cool 'n Quiet would have no chance to even make an impact as all cores are being utilized at full speed. Under load the Quad FX system pulled 456W on average, a full 73% more than our Kentsfield testbed.
If we look at performance per watt, the Quad FX loses big time. We specifically chose to look at our WME encoding test because the performance of the FX-74 and QX6700 is pretty close. What you're looking at here is the best case scenario for the Quad FX's performance per watt; in applications where it's significantly slower than Kentsfield the performance per watt will be even worse.
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Neosis - Friday, December 1, 2006 - link
However (in my opinion) since all these four cores share the same 8MB L2 cache and Intel's memory disambiguation forces all cores to use L2 cache more, additional latencies are not significant as the Amd's 4x4 platform. But you are right again that connecting the dies through the FSB requires all die to die communication to go back to the Northbridge and into the system memory. That can be a serios perfomance issue when Amd has competing processers.
mino - Friday, December 1, 2006 - link
Kentsfield == 2 Conroes stuck on 1 FSB. They have _separate_ 4M L2 cache. No 8M L2 on the horizon..Neosis - Thursday, November 30, 2006 - link
Where is edit button?The first sentence should be "I think ..."
Neosis - Thursday, November 30, 2006 - link
I don't think AMD can compete with Kenstfield even with this platform. Enthuiasts usually don't care power consumption and heat problems. A water cooling system (with a large radiator and a strong pump) will do just good. The main concern is neither the power consumption nor the heat problems. When you install two dual core processor, you are going to have performance down due to the increased latency. Nearly in all benchmarks Intel is leading. No suprise that only one motherboard manufacturer was in on.Even though I'm an AMD user, I don't see any particular reason people will buy this. But I can say why not:
- no one knows how long Amd will support this platform. In the past years Amd has beem changing sockets almost each year and half. We know Socket Am3 will use Ddr3.
- pricing
Griswold - Saturday, December 2, 2006 - link
Well the first part isnt quite true or very precise, as for the second part, we also know that AM3 CPUs will run in AM2 sockets (but not vice versa). On top of that, we're talking about Socket F here and not AMx.
If you want to name a good reason to not buy this: The other option is just that much better. End of story. If you want quad AMD, wait 6 months.
Gigahertz19 - Thursday, November 30, 2006 - link
On black Friday I was at Circuit City and some store employee near me was telling this woman who was looking for a computer to make sure she buys a computer with a AMD processor because their faster and all around better. I couldn't stand there and let him lie to that woman so I went over there and told her she needs to buy a comp with a Core 2 Duo and gave my reasons. Then the Circuit City guy went into this rant about AMD and the 5000+ processor and how it's the best, haha apparently he hasn't updated his knowledge for quite sometime. I could of stood there and argued it but I just said okay and walked away, didn't walk to make a scene...plus how geeky would that be arguing over processors in the middle of a store where customers are.Anyways looks like Intel Core 2 Duo tech is the thing to get. I'm stilling running a old XP-M overclocked with a DFI Socket A mobo. I want to upgrade to Core 2 Duo sometime soon probably get the Core 2 E6600 only because it has 4Mb cache and the slower speed ones don't. Overclock that baby to 3GHz which should be a given with the right mobo like the Evga one and I'll have a awesome system, probably buy a X1950 XT or Pro for around $250 then upgrade to DX10 when it gets cheaper.
madnod - Thursday, November 30, 2006 - link
i am really into AMD and i was buying AMD since the last 4 years, but this time intel isreally pushing ahead.there is a major thing that intel is doing these days and it's really funny to see the way AMD is responding to that, it kinda remind me of the 3DFX approach, start stacking more things that u already have and wish that things will be better.
AMD should expedite their transition to the newer CPU desgin, the current K8 architecture can't keep up with the core technology.
THX - Thursday, November 30, 2006 - link
Very nice tests. I can't believe the power draw AMD is dealing with here.Ecmaster76 - Thursday, November 30, 2006 - link
The pin count of AM2 probably isn't an issue. It has as many pins as 940 which can handle multiple HT links and dual channel memory.AMD just moved it tot he other socket to people from buying the bundled CPUs and selling them individually for a profit. The 2.6 GHz model for example runs about $100 less per chip than the standard X2 does.
punjabiplaya - Thursday, November 30, 2006 - link
Are we going to see updated benchmarks with 64 bit performance and/or Vista and when there is a BIOS fix for the NUMA issues on the board (not the WinXP shortfalls as far as NUMA is concerned, Vista should take care of that)?Just curious.