Intel Core 2: Is high speed memory worth its price? Does the Intel Core 2 need fast DDR2 memory to perform at its best? In this article we compare different memory speed and timings to provide you with the answer. Read on to find if cheap memory is enough to feed the Conroe http://www.madshrimps.be/gotoartik.php?articID=472 |
What about overclocking? Are there dividers for Core 2 865 boards as well so we can still clock our Allendales through the roof with cheapskate ram? |
I don't know for other boards, I975 allows for quite an adjustment range for divider settings http://www.madshrimps.be/articles/In...otke-12981.jpg Memory Frequency; 333 / 400 / 533 / 667 / 800 Mhz so with cheap 533 / PC4200 you run run it at 333 and get quite a bit of headroom for overclocking without the memory running out of specifications. for the newer P965 and older 865 I can only hope there are similar settings, don't know, google ? :) |
I've updated the last page with info on the decrease of performance with PC5300 vs PC4200, thanks to Sintel for the clear explanation: The Core 2 has a front side speed bus (FSB) of 266Mhz x 4 (Quadruple) “1066Mhz”, the ram is running at 266Mhz x2 (Dual Channel) x2 (DDR) = “1066Mhz”, so with PC4200 memory and FSB are running synchronized. When you use PC5300 you are no longer running synchronous with the FSB and a factor of x1.25 has to be used. The older Athlon XP from AMD also displayed this decrease in performance when running memory asynchronous, where memory latency is more important then memory bandwidth; the Core 2 technology is similar in this aspect. With the Pentium 4 the pipe lines were longer and the effect of running asynchronous which increased latency was masked. By running the memory synchronous to the FSB you have the least amount of latency and thus performance is at its best. Why is PC6400, which is also running asynchronous faster then? Because the memory latency and speed is now that much higher that it compensates for the loss of running asynchronous and overall performance does increase. PC5300 worked great with Pentium 4 but it should be avoided when running Core 2. |
it's still a bit more complicated it seems: http://www.bleedinedge.com/forum/sho...016#post180016 Quote:
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Greetings! How can you say that the reason is the synchronicity between the RAM and the FSB, if you only tested one FSB? |
if you read through the complete text of the forum post linked above, you'll see that by changing the CPU native FSB and thereby also the north bridge strap, you shift the 1:1 sync from 400 to 533 to 667; but even at 667/1333(FSB) the performance is lower, when running in sync, as the NB is running on higher latency to obtain this speed, thereby decreasing performance. if you CAN change the NB strap, you can alter the NB strap setting, forcing it to run either slower/faster to give you more headroom for overclocking, but that something for a different article. :) |
mmm, I ordered my Core 2 Duo which will arrive second half of August. I ordered 2GB dual channel G.Skill memory DDR2-800. I took that due to the timings offered (4-4-4-12) at that speed AND it being the lowest priced (near 180€). Was that a good move? Or was there something better to be bought? If I could clock down the timings to something like 3-3-3-8, would it be interesting enough to try it, or just a waste of time? |
if you are planning to overclock, the headroom of the DDR2-800 will allow you to run 1:1 while you increase the FSB |
Greetings! But then, how to explain the weird behaviour of Quake4? The performance at 800*600 rises with faster memory, regardless of being 1:1 or not. From the article: Quote:
So, other C2D chipsets may show a different behaviour, no? |
even with VIA there was an noticeable performance increase if both CPU:MEM were running in sync :) Quote:
the Quake 4 results mirror the synthetic Sisoft Sandra benchmark where raw memory BANDWIDTH wins over lower LATENCIES :) you can compare 667 5-5-5-15 vs 533 3-3-3-8 and will see the result difference remains consistent in all benchmarks. |
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liar! ;) |
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http://www.xbitlabs.com/articles/chi...cketa-400.html Particularly, the FSB333 tests: http://www.xbitlabs.com/articles/chi...eta-400_7.html Where you see the KT600-FSB333-DDR400 faster than KT600-FSB333-DDR333. The nForce2 chipset was built to achieve better performance at 1:1. Will look for the PDF. Quote:
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what was your old username? article I linked seemed to be a bit dated, your link is better, thanks! And for the Core2 the same still applies, as DDR2 800 is faster then DDR2 533 , although DDR2 800 is not running in sync:) raw bandwith overcomes the lower latencies, but if you check PC4200 with very tight timings (3-3-3-8) you see it's not trailing far behind PC6400. |
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Granted, every enthusiast had a nF2, not a KT600 motherboard. If it had to be compared to any CPU it would be the A64, for its love for tight timings. Per this article: ;) http://www.madshrimps.be/?action=getarticle&articID=325 Found the nForce2 PDF: http://www.nvidia.com/object/LO_20021105_7263.html Check at the bottom of page 2. |
"No users found matching those criteria." for Impar ... weird can you find your older username in the memberlist? http://www.madshrimps.be/forums/memberlist.php?s= I could just change your current nickname to the one you want too:) well.. tight timings AND running in sync, as even with tight timings the 667 does not do better than 533 :) |
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I still think that the comparison to Athlon XP shouldnt be made and that the article should have been made using other FSBs than the default (lets face it, Madshrimps readers wont run theirs C2D at default). Also, and this is a picky one, when I read PC3200 I still think DDR-400, not DDR2-400. PC2-3200 is the acronym I relate to DDR2-400. |
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we'll have an overclocking Core 2 / DDR2 article pending, this one is for mainstream and does help people a lot; just today a friend send me his new PC config, he doesnt overclock, he mixxed his E6600 with DDR2-800 which sky rocketted the price (€180 for 512Mb :o) so .. yes this article is for our readers, which (hopefully) doesn't solely include overclockers but PC enthusiasts and mainstream also |
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If you can, on the upcoming C2D overclocking article, test different RAM speeds/timings. I know its a lot of work... Regarding username, thanks. :ws: |
well, the ram timings/speed have been mostly tested here, what we'll try is to see if a higher FSB on CPU helps performance (in combination with lower multiplier to keep CPU speed the same) with Athlon XP this FSB increase paid of well, it worked good with P4 too, less with Athlon 64 (if not at all) so it'll be interesting to see how the Core 2 will handle this; here is a test by Hardware France (translated) which looks at timings/DDR2 speed and FSB speed: http://www.behardware.com/articles/6...-duo-test.html Quote:
If I started a poll and the "mainstream user" got 0 votes, it would actually prove that point :p |
The sync thing is mainly on how the memory controller is built, different memory controllers have different charasteristics. Yes you can argue that VIA had memory controllers which showed a very marginal performance improvement when running async with faster memory, however, if you compare the scores vs nforce sync, you will see that for example FSB333/RAM333 on nforce will perform faster than FSB333/RAM400 on VIA on about every benchmark that isn't bottlenecked by some other chipset factor. The comparison with the AthlonXP is in my opinion very valid because it was the only 'short pipeline' cpu where running memory async was an option and which had a FSB/memcontroller architecture. The A64 is on an inherently different, more modern platform and does NOT have the same issues, yes it does have a short pipeline and a dependence on memory timings, but the memory controller runs at a factor of the full processorspeed, the hypertransport link to the chipset can not be compared to a FSB and doesn't get used at all in cpu/memory communication. The FSB is entirely eliminated from the equation so you don't have async issues, in essence on A64 the memory always runs "in sync".. |
Greetings! Well, nForce and C2D look much better at DDR2-800 than at slower RAM speeds: http://www.anandtech.com/printarticle.aspx?i=2820 |
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