Investigations into Socket 939 Athlon 64 Overclocking
by Jarred Walton on October 3, 2005 4:35 PM EST- Posted in
- CPUs
Memory Options
Memory has been a major part of overclocking since we shifted to locked CPU multipliers back in the Athlon/Pentium III era. With the move to DDR RAM on the Athlon and Pentium 4, it has become even more important. Since all processors other than the Athlon FX chips (and Pentium M) are multiplier locked - at least on the high end of the scale - increasing your CPU clock speed means that you have to increase the system/CPU bus speed. If your default bus speed is 200 MHz and you have a 10X multiplier, you end up with a 2000 MHz processor. Raising the bus speed to 220 MHz would give you a 2200 MHz CPU, but it would also require memory that could run at DDR440 speeds. That's the way it normally works, and so we have unofficial memory speeds of up to PC4400 (DDR550) that allow you to overclock your bus, CPU, and RAM beyond the standard specification.
However, there are alternative methods of overclocking that may not require ultra high speed RAM. High speed RAM generally costs quite a bit more, and if your goal in overclocking is to get higher performance without spending a lot more money, doubling the cost of RAM defeats that purpose. We'll be looking at the impact of using the lower memory ratios in order to keep standard PC3200 at or below DDR400 MHz speeds. This means that you could use any PC3200 memory. There will be some performance loss, but the question is: how much? That's what benchmarks are for...
On the other end of the RAM spectrum, we find the high performance and high cost parts. Yes, you can buy some untested DIMMs with similar ratings to the high performance RAM for less money, but we're more interested in exploring guaranteed RAM speeds in this article, so we won't be taking that route. However, even if you can't reach the RAM speed that you want, our value RAM will serve as a minimum performance metric. At the high end, there are a few major contenders.
First, there's the high performance, high voltage RAM like OCZ VX and Mushkin Redline. (They probably use Winbond CH5 blanks, and we'll just use CH5 to refer to this memory from here on out. We could be wrong on the actual chips used, however.) You'll need a motherboard that can supply up to 3.5V to the RAM to get the most out of such memory, with 2-2-2-6 1T timings possible for as high as DDR533, give or take. You'll also want to get active cooling on the memory if you go this route. The next option is to grab some of the re-released Winbond BH5 DIMMs, which are similar to CH5 in that high voltages allow for 2-2-2-7 1T timings up to DDR500 speeds. The price and performance of these two options are roughly equivalent, with the CH5 generally reaching somewhat higher speeds. The drawback of CH5 is that it also requires at least 3.0V just to run at 2-2-2 timings and DDR400 speeds, where BH5 can do the same with only 2.6V. The final option is to go for the tried-and-true Samsung TCCD (or TCC5) DIMMs. You'll sacrifice some performance and have to lower the timings as RAM speeds increase, but the good news is that you won't need more than 2.80 to 2.90V to reach maximum clock speeds. You can also get TCCD DIMMs up to DDR600 and even beyond, which serves to counterbalance the better timings of BH5/CH5. The cost of Samsung TCCD is roughly the same as the other two choices.
So, which RAM do you choose? There are several factors, and in order to keep the number of benchmarks from rapidly bloating, we only used one type of value RAM and one of the performance RAM options.
For our high end RAM, we used what we already had available: OCZ Rev. 2 Platinum (TCCD memory as opposed to the newer TCC5 memory). One of the benefits of this RAM is that it doesn't run as hot as the BH5 and CH5 when overclocked, so active cooling won't be required at maximum clock speeds. Active cooling means more noise from your PC, and while few overclocked systems are truly quiet (without resorting to water cooling), many people will agree that adding more fans to the case isn't really desirable. This doesn't mean that BH5 or CH5 is a bad choice, and in many instances, either would be slightly faster than TCCx RAM.
The final pieces of the overclocking puzzle are the choice of case and power supply. Case selection influences (to a large degree) the number and arrangement of fans that you can use for cooling, though anyone with a bit of skill and a Dremel tool can add extra fans if needed. We'll talk a bit about heat sinks and fans for CPU cooling as well. First, let's start with the power supply, as it is more directly comparable to the components that we've covered so far.
Memory has been a major part of overclocking since we shifted to locked CPU multipliers back in the Athlon/Pentium III era. With the move to DDR RAM on the Athlon and Pentium 4, it has become even more important. Since all processors other than the Athlon FX chips (and Pentium M) are multiplier locked - at least on the high end of the scale - increasing your CPU clock speed means that you have to increase the system/CPU bus speed. If your default bus speed is 200 MHz and you have a 10X multiplier, you end up with a 2000 MHz processor. Raising the bus speed to 220 MHz would give you a 2200 MHz CPU, but it would also require memory that could run at DDR440 speeds. That's the way it normally works, and so we have unofficial memory speeds of up to PC4400 (DDR550) that allow you to overclock your bus, CPU, and RAM beyond the standard specification.
However, there are alternative methods of overclocking that may not require ultra high speed RAM. High speed RAM generally costs quite a bit more, and if your goal in overclocking is to get higher performance without spending a lot more money, doubling the cost of RAM defeats that purpose. We'll be looking at the impact of using the lower memory ratios in order to keep standard PC3200 at or below DDR400 MHz speeds. This means that you could use any PC3200 memory. There will be some performance loss, but the question is: how much? That's what benchmarks are for...
On the other end of the RAM spectrum, we find the high performance and high cost parts. Yes, you can buy some untested DIMMs with similar ratings to the high performance RAM for less money, but we're more interested in exploring guaranteed RAM speeds in this article, so we won't be taking that route. However, even if you can't reach the RAM speed that you want, our value RAM will serve as a minimum performance metric. At the high end, there are a few major contenders.
First, there's the high performance, high voltage RAM like OCZ VX and Mushkin Redline. (They probably use Winbond CH5 blanks, and we'll just use CH5 to refer to this memory from here on out. We could be wrong on the actual chips used, however.) You'll need a motherboard that can supply up to 3.5V to the RAM to get the most out of such memory, with 2-2-2-6 1T timings possible for as high as DDR533, give or take. You'll also want to get active cooling on the memory if you go this route. The next option is to grab some of the re-released Winbond BH5 DIMMs, which are similar to CH5 in that high voltages allow for 2-2-2-7 1T timings up to DDR500 speeds. The price and performance of these two options are roughly equivalent, with the CH5 generally reaching somewhat higher speeds. The drawback of CH5 is that it also requires at least 3.0V just to run at 2-2-2 timings and DDR400 speeds, where BH5 can do the same with only 2.6V. The final option is to go for the tried-and-true Samsung TCCD (or TCC5) DIMMs. You'll sacrifice some performance and have to lower the timings as RAM speeds increase, but the good news is that you won't need more than 2.80 to 2.90V to reach maximum clock speeds. You can also get TCCD DIMMs up to DDR600 and even beyond, which serves to counterbalance the better timings of BH5/CH5. The cost of Samsung TCCD is roughly the same as the other two choices.
So, which RAM do you choose? There are several factors, and in order to keep the number of benchmarks from rapidly bloating, we only used one type of value RAM and one of the performance RAM options.
Clck to enlarge.
For our high end RAM, we used what we already had available: OCZ Rev. 2 Platinum (TCCD memory as opposed to the newer TCC5 memory). One of the benefits of this RAM is that it doesn't run as hot as the BH5 and CH5 when overclocked, so active cooling won't be required at maximum clock speeds. Active cooling means more noise from your PC, and while few overclocked systems are truly quiet (without resorting to water cooling), many people will agree that adding more fans to the case isn't really desirable. This doesn't mean that BH5 or CH5 is a bad choice, and in many instances, either would be slightly faster than TCCx RAM.
The final pieces of the overclocking puzzle are the choice of case and power supply. Case selection influences (to a large degree) the number and arrangement of fans that you can use for cooling, though anyone with a bit of skill and a Dremel tool can add extra fans if needed. We'll talk a bit about heat sinks and fans for CPU cooling as well. First, let's start with the power supply, as it is more directly comparable to the components that we've covered so far.
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JarredWalton - Wednesday, October 5, 2005 - link
Sorry if I missed this in the article. The reason a 3200+ may be better is the 10X multiplier vs. 9X. Sure, the DFI board used worked pretty well at either setting, but there are many boards that won't handle much above 250 MHz CPU bus stably. Needless to say, there's a reason 2800 MHz was only included at one setting. While it still wasn't stable, it would actually run most benchmarks at 10x280. 9x311 wouldn't even load Windows half the time. The extra $50 for added flexibility is also nice: you can try 9x300, 10x270, PC3200, PC2700, etc. to find the most stable, highest performing option.Bakwetu - Wednesday, October 5, 2005 - link
Thanks for a great article. I haven't been following the development so carefully since I upgraded last time (with one of the last unlocked Barton 2500+), so this article was a most welcome refresher for me, as I will probably get a x2 3800 rig in the near future.Last time I checked using the naked fingertip to smear out the paste was a big no-no. I have always used either a washed razorblade or fingertip in a clean plastic bag. The Arctic silver once sold without silver was a faked, copied product as far as I know. The real stuff in its many forms over the years has definitely shown that it is a good product.
javalino - Wednesday, October 5, 2005 - link
Frist , great article, Jarred.Second, i m an anand fan since i remember (1999-2000).
Third, Since yours conclusion focus on a dilema about overclock, why spend to much in an overclock symtem(or on a powerfull system) if you target is at games ? (wich is a GPU limited). An 125 bucks , like you said, will be more usefull in a video card.
My idea is an article, about "Benefits, Costs, and Lessons Learned" about build a system for games. How much will be a performance gain from systems running high end cards ,at high resoltion and configurations ( like 1600 x 1200, and with an extra 4xAA 16XAF), with differents system . A FX VS 64(overclock) VS P4 (over) VS P-M VS AMD XP (over of course), for example. The conclusion will be, how much is "needed" to pay for a decent game machine wich is possible to play all current games(and maybe future) with great image quality and performance.
Maybe the answer is obvious, go with the best FPS/price option possible, or maybe not.
AtaStrumf - Tuesday, October 4, 2005 - link
Great article Jarred!!! I really like your choice of value parts and how you criticaly assesed the results based on the bang-for-the-buck. And finally you did away with pages and pages of bar charts, and combined them into line-scaling charts. How long have I been asking for something like that??? Now we can finally see the REAL difference (or lack of it), and analyse results properly, without having to go back and forth between tens of bar charts. Tell Anand to upgrade your graphing engine ASAP.I am a little worried about those voltages though. This sure looks like a bad chip to me (OC wise). WAY too high voltages. I would not go over 1,45 - 1,50 V or else you risk screwing up the chip. You see the memory controller on the chip doesn't like too high voltages and though it will still work, the chip will get slower eventually. Hard to explain really but I know my new 2,2 GHz A64 is faster and much cooler than my old 2,4 GHz A64 (same core - Newcastle, same cooer, same RPM, same case, same ...), which I bought from some crazy overclocker (last time BTW). The 2,4 GHz one gave me really shitty results in FAH for weeks. That's the only explanation a have so far anyway. Maybe you can do an investigaion into this -- burn in one A64 Venice at say 1,6V 24/7 for a few weeks and let's see what happens. I just don't have the $$$ and time to take the risk. I'd be very happy to hear from other forum members on this as well.
Anyway, glad to see at least part of AT is back to the high quality standards we were used to.
AtaStrumf - Tuesday, October 4, 2005 - link
Or maybe it's the SOI process that is to blame for not taking high voltages too kindly, or maybe both, don't know yet, but I would definitely advice caution goint over 1,5V (default for 0,13 mikron SOI chips). Just think about it, that's already a 15% increase. +10% is usualy max that is still considered safe.You just posted that this chip seems to have changed it's behavior (better OC). That may have something to do with the high voltages and it may not be all good. I'd suggest testing it again in a few benchmarks and comparing the results.
JarredWalton - Wednesday, October 5, 2005 - link
Working on it. I think I ended up benching at 1.850V for the 10x280 setting and then not dropping voltages as much as I was supposed to. I'm a little skeptical that a CPU would get slower, though. Usually, they work or they fail. We'll see.My thought on the "safe limit" though: what voltage does the FX-57 run at? Whatever it is, at 10 to 15% to that and you're probably still okay. Good cooling will also help; on the stock HSF, I'd be a lot more nervous going over 1.550V.
OvErHeAtInG - Tuesday, October 4, 2005 - link
Very useful article - thorough yet concise. And I would like to toss in another request: Add to the test a ULi-based motherboard (such as the recently reviewed ASRock 939Dual-SATA2). How do these Venices overclock when you can only feed them +.05v? As I recall the standard AT Clawhammer was used in that review.That would be hugely useful to a lot of us wanting to transition to A64. While the thing to do is probably just get a DFI or other top-end oc'er, what to do for those of us who are not yet ready to upgrade GPUs? On second thought: you could simulate the ASRock motherboard by simply setting the Venices to the lower voltage, on the DFI board, and testing for the max overclock on that. I think that would vary quite a bit from chip to chip, but just to get an idea - how much of a disadvantage is being limited in your voltage? Food for thought.
JarredWalton - Tuesday, October 4, 2005 - link
I played around with voltages a bit more last night. It seems like I can hit about 2.40 GHz with only increasing the CPU voltage to 1.40V, though I didn't run all of the benchmarks to fully test that config. I'm not sure if the CPU has changed behavior over the past month, or if I was just too liberal with the voltages initially.For the ASRock, that Wes managed to get a 500 MHz OC even with the minimal voltage adjustments is promising. Truth be told, the DFI Infinity seems to undervolt the CPU slightly, so 1.500V actually shows up as closer to 1.455V. If the ASRock is exact with the voltages, or even a bit high, I think a 2.4+ GHz overclock is a reasonably safe bet.
OvErHeAtInG - Wednesday, October 5, 2005 - link
Thanks for the info, Jarred. I'm sure there's a thread on this somewhere.... :)araczynski - Tuesday, October 4, 2005 - link
i haven't seen a better argument for not wasting money on the 'better' memory in ages.with those kinds of 'gains' i congratulate the companies for milking everyone with their markups for the 'higher end' components.