AMD Athlon 64 & Athlon 64 FX - It's Judgment Day
by Anand Lal Shimpi on September 23, 2003 1:25 PM EST- Posted in
- CPUs
Where does 64-bit help?
Although the performance that will sell the Athlon 64 today has nothing to do with this, the 64-bit part of the equation will definitely play a role in the processor's future. With no final release of the 64-bit version of Windows XP, there is no popular OS support (we will touch on Linux support as well as Win64 support shortly) and no real application support at this time, but where will the 64-bitness of the Athlon 64 help?
There are three main categories that you can split up the performance benefits into: 32-bit applications running on a 32-bit OS, 32-bit applications on a 64-bit OS and 64-bit applications on a 64-bit OS; we will be analyzing each one of these scenarios individually.
Case 1: 32-bit apps under a 32-bit OS
At the launch of the Athlon 64, the predominant operating environment will be running 32-bit applications under a 32-bit OS. All performance benefits the K8 architecture will show here are courtesy of the on-die memory controller, improved branch predictor, higher clock speed and more robust TLBs - none of the performance improvements you'll see in this case will have anything to do with the 64-bit capabilities of the processor.
Case 2: 32-bit apps under a 64-bit OS
When Windows XP 64-bit Edition is officially released (a public beta is due out at the time of publication), many users will be running their 32-bit applications under the 64-bit OS.
Outside of the performance improvements that we just outlined in Case 1, there are a couple of additional benefits the Athlon 64 may offer users. Currently under Windows, although you have a physical memory limit of 4GB, any given process can only use up to 2GB of memory; the remaining 2GB is reserved for use by the OS. With the 32-bit applications under a 64-bit OS scenario, each 32-bit application could be given a full 4GB of memory to work with, instead of being limited to the 2GB Windows process size limitation. Unfortunately this benefit isn't really "plug 'n play" as the application would have to be aware that it can use the added memory, which in the vast majority of cases would require a new patch to be made available.
The second benefit the Athlon 64 could offer in this scenario comes from the availability of additional registers. Although the 32-bit application would still only be compiled to use the regular set of 8 general purpose registers and standard set of FP and SSE2 registers, the 64-bit OS would be able to reference and use all of the registers at its disposal. The performance benefits that you would see here exist in any sort of task handling that the OS would be doing (switching between applications) as well as just regular Windows performance. Granted that the performance improvements seen here should be negligible, considering the extra overhead that does exist when running 32-bit applications in a 64-bit environment (more on this in a bit).
Case 3: 64-bit applications under a 64-bit OS
The final scenario is the one that shows the most promise, yet has the least amount of application support today - running a 64-bit app under a 64-bit OS. Here, the benefits are numerous; not only do you get the performance improvements courtesy of the Athlon 64's architecture, but each application now has full access to the increased number of registers and each application can use much more than 4GB of memory.
Although the Athlon 64 can support 64-bit memory addressability, for demand reasons it only supports 40-bit of physically addressable memory - or ~137GB, not exactly a limiting factor at this point.
The performance improvements developers are expecting to see under this final scenario has been estimated to be in the 10 - 20% range in tasks that are not memory bound, meaning those areas where the application is using less than 2 - 4GB of memory in the first place will still see sizable performance gains courtesy of the availability of more registers. We will investigate a few of these scenarios to substantiate (or refute) these claims later on in the article.
Performance improvements where you are memory bound will be even more impressive; just think about how slow swapping to disk is and how much faster keeping everything in memory makes your computer.
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Anonymous User - Wednesday, September 24, 2003 - link
(to #87)xbit labs did a pretty decent review and used "performance" platforms for the CPUs but left out VIA chipsets which people are saying are faster than nVidia for the AMD64 tests. Their conclusion was unbiased pointing out pros and cons of each processor type - I especially like the closing statement of how the current manufacturing processes are getting tapped out and it will be up to the new 90 nanometer process to get increased performance.
Tom's Hardware used the absolute best platforms under their optimal settings (i.e. the latest motherboards including both from nVidia and VIA for AMD, the latest optimized drivers, 4 x 256 DDR for Intel vs. 2 x 512) the way real enthusiasts would set their platforms up. Tom's conclusion tends to lean towards Intel with the P4 3.2 EE winning more tests than the Athlon FX - he did update his benchmarks and took out most of the overclocked P4 scores and I still count the P4 3.2 EE winning 26 benchmarks vs the Athlon FX winning 15.
HardOCP used an Intel Bonanza motherboard which doesn't really allow the P4s to perform at their best IMO - lower memory timings cause the Intel motherboard to perform slower than the 875 boards from ASUS and Abit. Their conclusion was that the new AMD chips are pretty good but AMD is still in a tight spot.
Extremetech also used the latest optimized platforms and also included nVidia and VIA chipsets. Their conclusion was pretty unbiased and left it to the reader to make their own choice.
Anonymous User - Wednesday, September 24, 2003 - link
I still can't understand *why* people are hyping the emergency edition P4. You can't buy the chip and won't be able to for at least another two or more months. By the time the chip comes out it's already old news since the FX53 and Athlon64 3400+ will have already begun shipping with Prescott not too long after (well dunno about Prescott since those comments at IDF to the tune of a 3.2Ghz P4EE outperforming a 3.2Ghz Prescott don't seem good to me). Not to mention the fact that even against the current *available* processors it can't beat the FX51 in overall performance. What exactly is the good thing about this chip ATM?Anonymous User - Wednesday, September 24, 2003 - link
He was talking about the manufacturers when talking about credibility. Look at PM Forum part 2 just for an example, every single one of them considers AMD still being a niche player even with AMD64 and Intel being the technology leader. Don't forget that these AMD64 processors were supposed to come out over a year ago, but they weren't able to deliver at all. If they had, this would be a much different market than it is now. You should know by now that what fanboys believe to be the trends in the marketplace is completely different from reality.Anonymous User - Wednesday, September 24, 2003 - link
#16CREDIBILITY
What on earth did Anand mean about AMD's loss of credibility? According to who? I mean, whatever you make of the P rating, who could possibly think that the XP wasn't a credible processor (even if the accuracy of the ratings exhibited slippage over time) or that the 64 wouldn't be a major improvement?
What was he trying to say by droning on and on about lost credibility? I really have no idea. Who was going around saying AMD wasn't "credible"? And what does that mean?
Anonymous User - Wednesday, September 24, 2003 - link
(this is #80)..I just read the X-bit labs review and it was a very long and in depth review. I think you guys should and read it and give me your impressions about it.
Peace,
Kevin
legionosh@msn.com
Anonymous User - Wednesday, September 24, 2003 - link
This is the tiniest athlon64 test I've ever seen. Not only is it way too small to make a fair projection of amd's capacitys but you've not tested the P4 EE ... I think that this must be the worst review ever made by you guys...Anonymous User - Wednesday, September 24, 2003 - link
#83..(this is #80) There are fanboys on both sides of the fence here. I think I tried to be as close to unbiased as I could, though I still think Toms benchies always seem skewed in a bad way. And in all fairness, if he oc'd his P4ee to 3.6, why not OC the AMD chips? Seems he's playing favorites to me..
The smart people always buy what is the best deal, regardless of the manufacturer (though almost everyone has a brand of something they won't buy again, regardless of product (clothing, food, etc..).
I currently have a P4 2.0a OC'd to 2.4 (took a new mobo to get there..the soyo just didn't cut it), so my soon to be here 2500+ and Nforce2 mobo may surprise the intel fanboys, but then I am not a fanboy. I was going to go with a 2.4c and Abit IS7-G but there was about a $120 price difference so I opted for a more economical route..(and if I can get 3200+ performance out of a $94 CPU that won't hurt either).. :-)
Anyway, I agree the fanboys on both sides need to read the facts and stop the bashing. It gets old fast and only shows ignorance.
I think the P4ee and FX are just too much for the mainstream/general public. VERY few people (well that I know anyway) have $800 just to blow on a CPU, plus any additional hardware needed (mobo, ram, etc) on a whim, so to me it seems the test will be how the 64 compares to the prescot. I also think AMD needs to drop the 64 price, but maybe that's just me.
And like it or not fanboys, there will almost always be tests where one CPU always wins over the other so take the tests with a grain of salt (this does apply to both sides of the fence).
When tax time rolls around in march or so if the 64 is price competitive to the P5/prescot and performance competitive I just may go that route. I imagine by then the new P5/prescots (not the soon to be out socket 478 variety) will be out and needing a new mobo also, so a mobo purchase looks to be in my future anyway.
But if the prescot blows away the 64 and is priced similiarly then that's where my money will go.
But again, like I stated previously, we do not want a "one choice" situation. That just bodes poorly for us, the consumer. So we have to think that AMD will do well. If not, the future will be bleak for u (remember we are only this far along due to the XP/P3-P4 battle that raged well over 2 years (correct?)..
Otherwise may might just now be getting the infamous P4 CPU....
..Just something to think about..
Peace,
Kevin
legionosh@msn.com
Anonymous User - Wednesday, September 24, 2003 - link
It is very difficult to evaluate the performance or value of the Athlon 64 chips. It is not unlikely that most cpu demanding apps like video processing and 3d rendering will support 64 bit once more developers and users go over on Athlon 64. But untill then there is a draw between P4 3.2+ and FX-51. A stable motherboard is at least as important as the CPU.Anonymous User - Wednesday, September 24, 2003 - link
Wow, this is the most fanboys I have ever seen in one place. How nerdy do you have to be to be protective of your precious CPU brand you stand behind?I just buy what's the best deal at the time, and both the new AMD and Intel CPUs are damn fast and close in performance. But the fact is the Athlon 64 is out now, the new Intel CPU isn't.
Also you can look forward to future increased performance out of the athlon 64 to sweeten the pot. If I were to pick I'd definitely get the A64 over the P4EE.
That being said, I'm buying a p4 3ghz next month, and I currently have an Athlon XP 2500+.
You fanboys need to just stfu already, jesus.
Anonymous User - Wednesday, September 24, 2003 - link
Enough of this pressithot shite! Yes i sound like a fanboy which i am but i'm not sounding like one LOL...anyways..next year we will see "Athens" @ 0.9nm with a Dual-channel DDR-|| controller and of course an improved Hypertransport Bus..possibly HTB2 and i tell ya..not even tejas will keep up @ WIN 64-bit mode.