Athlon 64 Revision E: Unofficial DDR500 Support
by Anand Lal Shimpi on July 11, 2005 12:05 AM EST- Posted in
- CPUs
Final Words
Based on the tests that we’ve seen here today, AMD’s reluctance to move to higher bandwidth DDR2 offerings makes a lot more sense. The plain fact of the matter is that at the current clock speeds at which the Athlon 64 and X2 line are running, most desktop applications see virtually no benefit from higher bandwidth memory. It is possible that server usage models may show a greater performance boost, but it is highly unlikely for a mission critical server to be equipped with anything that isn’t an officially supported standard - especially memory.While some have been critical of AMD’s unwillingness to embrace DDR2 when Intel did, it would appear that the quest for more bandwidth simply wasn’t in AMD’s best interests. These Athlon 64 and X2 cores that we have here today are far better suited for use with low latency and lower priced DDR400 than anything that offers higher bandwidth.
Down the road, as CPU speeds and the sheer number of cores goes up, then higher bandwidth memories will definitely make much more sense. But for now, for the majority of the population, these new memory dividers won’t do much for you.
The performance improvements themselves aren’t tangible, but if you are trying to squeeze every last ounce of performance out of your system, then these new memory dividers offer you one more avenue to do so. If you have memory that can run at higher than DDR400 speeds without any reduction in latency, then by all means, explore the new dividers; just don’t expect them to change your life.
The one exception to the rule seems to be heavy multitasking scenarios. As we saw from our simple DVDShrink + Doom 3 test, when you run two very memory bandwidth dependent applications on a dual core processor at the same time, the benefits of these faster memory speeds really starts to show itself. We measured a 6.5% increase in performance in the aforementioned test, but next to no performance improvement in other lighter multitasking scenarios. As we continue to develop our multitasking benchmark suites, we will now start looking at how added memory bandwidth, made possible through these new dividers, changes the performance picture.
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Murthunder - Wednesday, July 13, 2005 - link
So what is the best memory for good overclocks yet is still stable? I originally tried a pair of Corsair TWINX1024-4000 Pro XMS sticks and my DFI LANParty UT nForce4 Ultra-D board would fail to post. I swapped the XMS for two 512MB sticks of Kingston ValueRam DDR333 c2.5 and my board has been stable ever since and faster than anything else I have. Any suggestions for an OC newbie who can't afford to simply keep trying different sticks until something works?Myrandex - Tuesday, July 12, 2005 - link
An interesting comparison would be an Athlon64 w/ DDR500 and a close to equivilently clocked Athlon64 w/ the HTT running at 250 to make the memory DDR500.semo - Tuesday, July 12, 2005 - link
#32, man if i could get those here in the uk (at that price).so Zebo, what do you mean that you can't run a64 in sync with memory. for example: if i get those:
http://www.ebuyer.com/customer/products/index.html...
and a dfi lanparty ultra d with a 3000 venice, would i be able to get a decent overclock?
Zebo - Monday, July 11, 2005 - link
It's really a shame anand did'nt do 3-3-3 like 99% of PC4200 sold runs @ 250...PrinceGaz - Monday, July 11, 2005 - link
Quite right Zebo, what this shows is that even the dual-core A64 processors when running multiple threads get little benefit from faster memory even at the same tight timings. Also as you say there is no such thing as a synchronous memory speed that might provide a performance advantage, as all memory speeds are in reality a divider from the CPU core speed. Running good PC3200 memory at or as much as it'll go above DDR400 2-2-2 is probably the best option. And if you want 2GB, get 2x 1GB modules so you can still run them at 1T command-rate as that's a better bet than four single-sided 512MB modules.One thing to bear in mind is if you enable Cool 'n' Quiet, that the memory may actually run faster at the lower CPU multipliers when it is set to other than DDR400 in the BIOS (DDR400 ensures the memory divider is always equal to the CPU multiplier).
Zebo - Monday, July 11, 2005 - link
http://forums.anandtech.com/messageview.aspx?catid...512 sticks
www.newegg.com/Product/Product.asp?Item=N82E16820146532
1024 sticks
www.newegg.com/Product/Product.asp?Item=N82E16820146545
#31 -- sure at a price, in the case of UTT is a pretty serious one if you ask me.. high volts.. high noise from fans.. high cost.. which may not be best usage of funds.. maybe that $150 saved is better spent on 7800GTX instead of 6800Ultra..or something like that.
AdamK47 3DS - Monday, July 11, 2005 - link
I'm a long time overclocker so a couple percent faster means something. If the option is there and it runs stable then go for it. All these little percentages add up in a heavily tweaked system. Overclocking the video, CPU, memory, and bus can all add up.Zebo - Monday, July 11, 2005 - link
PS I recommend Crucial sticks (not the 8T).. they have micron G abord..same as Ballistix for half price (but not speed binned so no guarantees).. Search around though.. many many including myself hit 2-2-2 with both 1024 x 2 and 512 x 2 configs.Zebo - Monday, July 11, 2005 - link
1. Keep in mind anand kept 2-2-2, low latency up to 250Mhz and *still* saw little difference.. fact is only one type, well two if you include anceint but still the best BH-5, can run this bandwidth and latency, Windbond UTT. This ram seems failure prone, watchout! The volts required, eg 3.5+, to attain those LL and bandwidth are extremely dangerous without active cooling on the ram. This ram is also "untested" (UTT) from windbond adding in an extra layer of uncertainty...Add in 2-3x the cost of regualar value muskin/corsiar/OCZ/Crucial which *can* all hit 2-2-2@200 with ~2.8V make this choice pretty lame considering the marginal payoffs. If you like cyber olympics and compete on the margins 0-5% by all means go for it...but 99% of y'all could find much better application of your funds.2. All other high bandwidth ram run crappy timings @ 250Mhz which will get stomped by LL @ 200. I've shown in forums you basically need 100mhz extra (not even 50) to hang with 200Mhz 2-2-2 when running ram 3-4-3, aka loose timings. Not worth buyin the high bandwidth stuff either when value muskin/corsiar/OCZ/Crucial which *can* all hit 2-2-2@200 with ~2.8V.
3. Overclcokers who want to run 1:1... there is no such thing as 1:1 in A64 archtecture.. all memory run async. So no problemo, no performance hit using 166/150/133 memsetting with value muskin/corsiar/OCZ/Crucial and shooting for 2-2-2@200 while clocking CPU to high heaven with proper HTT/FSB adjustments.
4. We see why AMD is'nt dieing for DDR2 this last year+.. and *when* they finally jump on board it will be at 667 instead of 533Mhz.. They can't afford the performance hit 533 will give, I'd be very surprised if 667 DDR2 is faster for AMD unless you run Crucials which is capable of 3-2-2.
In sum -- don't believe the hype. Get good cheap safe X2/A64 and DDR -- you'll be fast for a very long time.
robster3323 - Monday, July 11, 2005 - link
Is it possible to measure this stuff on a multi socket board? One of AMD's big selling points of HyperTransport is that other CPU's in other sockets can get to other memory faster. I wonder what impact these faster memories would have on socket to socket memory access?In other words socket one is direct connected to mem slot 1, the data in mem slot one is needed by a CPU in socket two, transiting the Hypertransport. How much benefit do the faster memories present?