Athlon 64 Revision E: Unofficial DDR500 Support
by Anand Lal Shimpi on July 11, 2005 12:05 AM EST- Posted in
- CPUs
AMD’s 90nm Athlon 64s have been almost everything that the enthusiast community has wanted them to be. Being little more than a die shrink, the 90nm chips are cooler, can run faster, and are cheaper to make than their 130nm counterparts. But the improvements didn’t stop with the move to 90nm. More recently, AMD has released their Revision E 90nm Athlon 64 cores, which featured a number of small improvements.
One of the biggest improvements to Rev E on paper was the added support for SSE3 instructions, originally introduced on Intel’s 90nm Prescott based Pentium 4. When the Rev E cores had first arrived on the scene, we took a look at the performance improvements offered by SSE3 support and came up empty handed .
There were a number of other improvements made to the Rev E core, including an updated memory controller - boasting support for mismatched DIMM sizes per channel, improved memory access performance for integrated graphics cores and a few other performance tweaks that AMD hasn’t gone into much detail about.
One such barely mentioned improvement was support for a handful of new memory dividers. With an on-die memory controller, AMD has to be particularly careful about adopting new memory technologies, as the wrong choice could leave them with a bunch of CPUs that are basically un-sellable. Over a year ago, AMD had been talking about bringing support for faster than DDR400 speeds to the Athlon 64 - assuming JEDEC would ratify the specifications. AMD waited until the very latest possible moment to decide on whether DDR2 or a faster DDR1 memory controller would be in their future, which is why it took them until just a few months ago to really start talking about DDR2 support. Potentially as a backup plan, the Rev E chips include unofficial support for memory faster than DDR400, without overclocking the Hyper Transport bus.
AMD obviously didn’t speak much about support for these higher speed DRAM options, mainly because they are not official specs, and thus, AMD doesn’t officially support them. But, the fact of the matter is that many folks have faster-than-DDR400 memory, and the new Rev E CPUs can now take advantage of that.
One of the biggest improvements to Rev E on paper was the added support for SSE3 instructions, originally introduced on Intel’s 90nm Prescott based Pentium 4. When the Rev E cores had first arrived on the scene, we took a look at the performance improvements offered by SSE3 support and came up empty handed .
There were a number of other improvements made to the Rev E core, including an updated memory controller - boasting support for mismatched DIMM sizes per channel, improved memory access performance for integrated graphics cores and a few other performance tweaks that AMD hasn’t gone into much detail about.
One such barely mentioned improvement was support for a handful of new memory dividers. With an on-die memory controller, AMD has to be particularly careful about adopting new memory technologies, as the wrong choice could leave them with a bunch of CPUs that are basically un-sellable. Over a year ago, AMD had been talking about bringing support for faster than DDR400 speeds to the Athlon 64 - assuming JEDEC would ratify the specifications. AMD waited until the very latest possible moment to decide on whether DDR2 or a faster DDR1 memory controller would be in their future, which is why it took them until just a few months ago to really start talking about DDR2 support. Potentially as a backup plan, the Rev E chips include unofficial support for memory faster than DDR400, without overclocking the Hyper Transport bus.
AMD obviously didn’t speak much about support for these higher speed DRAM options, mainly because they are not official specs, and thus, AMD doesn’t officially support them. But, the fact of the matter is that many folks have faster-than-DDR400 memory, and the new Rev E CPUs can now take advantage of that.
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ElJefe - Monday, July 11, 2005 - link
Well, I could say this would have been a great test if only one thing: to show the effect of TIMINGS on this. I know the OCZ had sickest tight timings, but im talking about the difference of say, using 4 single gig memeory modules and then messing around with the timings, showing which is best. I know at 1 gig, most of those l33t ram flashy types of dual channel matches drop off and kinda go into hum-drum land.If i had an X2 system it would have 2 gigs on two chips or 4 gigs on 4 chips. I couldnt see a dual proc system built for simply faster gaming, it's meant to be a cookie monster of processes.
KristopherKubicki - Monday, July 11, 2005 - link
bupkus: DDR2 comes with the M2 socket next year. At least, thats according to the roadmap.Kristopher
fishbits - Monday, July 11, 2005 - link
"The ceil() function is a pretty basic mathematical function that returns the smallest integer value greater than its argument..."Think that should be "greater than or equal to." ceil(10.0)=10. Not that it exactly matters much in this context. Anyhoo...
I'm glad AMD is further ahead of supporting mem speeds than needed, as opposed to playing catch-up. Additional options and capability for their future items will pay off down the road if not now.
brownba - Monday, July 11, 2005 - link
#1"keeps getting better and better."
huh? did you look at the benchmarks?
what is better?
Anand just showed us to save our money, we don't the very fastest ram, so I guess that is better.
Wesley Fink - Monday, July 11, 2005 - link
#2 - The OCZ PC3500 GX is specially binned BH5. Anand had planned to use VX memory but it was out of stock as this article was being developed. OCZ binned some BH5 at 3.3V for 2-2-2 operation at DDR500 to meet the requirements of this review and turned it around in a few hours. The point is that OCZ PC3500 GX will NOT all operate at 2-2-2 at DDR500. The OCZ VX and Mushkin Redline, on the other hand, are both rated 2-2-2 at DDR500 at 3.5V. The VX/Redline are based on Winbond CH5 blanks.Wesley Fink - Monday, July 11, 2005 - link
#20 - There is a new official DFI BIOS in the works that is to post soon. However, as I mentioned in the nF4 Ultra roundup there are over 60 BIOS revisions avaialble for the DFI nF4 boards. Oskar Wu of DFI has posted many of the BIOS' at www.dfistreet.com, the DFI Forum website, or in the Forums at www.xtremesystems.org.yacoub - Monday, July 11, 2005 - link
[In keeping with our recently growing practice,] "We chose three CPUs to investigate the impacts of these new memory dividers: [The three you are least likely to own]: the Athlon 64 X2 4800+ (2.4GHz/1MB L2), the Athlon 64 X2 4200+ (2.2GHz/512KB L2) and the Athlon 64 FX-57 (2.8GHz/1MB L2)."hehehe
ksherman - Monday, July 11, 2005 - link
I know this is going to sound like a dumb question, so here it is. Where did you get the BIOS update for the DFI board? I have that board, and their website only lists an update throung March, nothing as recent as July...Stinger22 - Monday, July 11, 2005 - link
One small correction..There is also an Athlon 64 3000+ that is a Socket 939 and is Revision E.
Hacp - Monday, July 11, 2005 - link
#13, I know of one other mobo that supports 3.3 volts and many other ram sticks can get 2-2-2-5 at ddr500.