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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Lonyo - Tuesday, October 4, 2005 - link
NO, DON'T, UNLESS YOU HAVE SOMETHING BETWEEN YOUR FINGER AND THE PASTE.Arctic Silver 5 instructions:
DO NOT use your bare finger to apply or smooth the compound (skin cells, and oils again).
JarredWalton - Tuesday, October 4, 2005 - link
Er... I didn't use Arctic Silver. Just the grease that came with the XP-90. I suppose there might be some thermal compounds that would be bad to touch. RTFM, right?Anyway, I'm not particularly convinced of the effectiveness of stuff like Arctic Silver. At one point, there was some story about how the AS batches for a while didn't actually contain any silver because the manufacturing company was skimping on costs (unbeknownst to Arctic Silver or their customers). I could be wrong, but I'm half-convinced AS is just a placebo effect. :)
poohbear - Tuesday, January 3, 2006 - link
that wasnt arctic silver, that was another company entirely (name eludes me since it was 2+ years ago)PrinceGaz - Tuesday, October 4, 2005 - link
Regardless of the compound, you shouldn't touch it with your finger for the reason stated-- skin cells and grease from your finger will be left on the grease and they act as a barrier that reduces thermal-conduction. The simplest way to avoid this is to put a clean plastic bag over your hand before touching the compound as that will prevent any contamination.Regardless of what you say about AS5, numerous reviews of thermal-compunds have shown that compared to the the standard grease supplied with AMD boxed processors, AS5 alone can lower temperatures by a few degrees C. Given how cheap AS5 is compared with a decent heatsink (like the XP-90), it is a very good idea to get some AS5 if also buying a better HSF than what is supplied with the CPU. Using the grease supplied with the CPU or heatsink is a false economy.
THG64 - Tuesday, October 4, 2005 - link
From my own experience I would say the BIOS is at least as important as the hardware itself.My A8N using 1004 final BIOS can run my A64 3200+ @ 2500 MHz (10 x 250, 1.4125V) and the memory at 208 MHz 1T (2x 1GB MDT DDR400 2.5-3-3-8). There is no chance to get a higher frequency running because I get memory problems at anything above 250 MHz (known as 1T bug). I tested the memory up to 217MHz so its not the limiting factor.
Over the months I made many attempts to upgrade BIOS to newer versions and had no luck at all. The last version were even more interesting because of the A64 X2 support. No chance to get even up to 250MHz base. Only the reason has changed it seems. I made a HD upgrade in between and switched from a PATA drive to a SATA drive. This made it even worse.
From 1005 to 1010 the BIOS limited the overclocking to 215 to 220 MHz through reworked memory options. After 1010 the memory isn't the problem anymore or at least not the main problem. Windows is loading until desktop and while the OS is still loading in background the HD LED stays on and the system freezes.
As mentioned in the conclusion the SATA controller seems to limit the possible o/c.
If there would be a lowcost PCIe SATA controller I would surely give it a try but at the moment I stay with 1004 and and more or less working SATA drive at 250 MHz.
lopri - Tuesday, October 4, 2005 - link
Hi,I'm currently running X2 4800+ in my rig. I think I can safely OC it to 2750MHz. But the thing is, my RAM can only do 220MHz.. And the mobo doesn't support anything other than DDR400, DDR333, DDR266. (A8N-SLI Premium)
What are the penalty of running a half-multi? I understand a half-multi won't get you the ideal memp speed, but in my situation I can make up for it by being able to raise the HTT some more. Basically I have following options.
CPU (Max): 2750MHz @1.475V
RAM (Max): 220MHz @2.75V (2-3-2-5-1T)
Therefore, here is what I can do:
1. 10.5 x 261: This gives me CPU 2741MHz and memory 211MHz. (from CPU-Z reading)
2. 11 x 250: This give me CPU 2750Mhz and memory 196Mhz. (from CPU-Z reading)
If I run Sandra I get almost the same CPU score from both settings. But I get a quite bigger memory bandwidth score from the Setting #1. In ideal world (that is, if only the final achieved speed matters), I definitely think the Setting #1 is better. I'd like to know if there is any "inherent" penalty attached to non-integer multipliers.
Could you help me out? Thanks a bunch!
lop
JarredWalton - Tuesday, October 4, 2005 - link
At one point in time, the half multipliers didn't really work properly. They were just hiding some behind-the-scenes memory and bus tweaks. CPU-Z apparently doesn't report this properly. Anyway, if the system runs stable in either configuration, take the configuration that performs better. (Run a variety of tests - memory bandwidth alone doesn't tell the whole story.)Sunrise089 - Tuesday, October 4, 2005 - link
How important is that XP-90? I am wondering if you all feel it is necessary, feel it is necessary for long term safety, or really feel the $45 would be better spent elsewhere?P.S. - Thanks Anandtech. 3000+, X-800 GTO2, and value RAM costs about $400, and overclocked performs about as fast as a stock speed FX-55, x850 xt-pe, and high-end RAM costing $1000+. Your last two updates alone could have saved someone $600.
JarredWalton - Tuesday, October 4, 2005 - link
You can get the XP-90 and a 92mm fan for about $40 shipped, but what's $5? How important is it? Well, I think you could probably get an extra 100 to 200 MHz relative to the retail HSF. I'll be working on testing a few cooling options in a future article. The XP-90 is quieter than the retail fan, but other than that... I'll have to see what difference it makes.da2ce7 - Tuesday, October 4, 2005 - link
When I over clocked my X2 3800+ I got up to 2.6ghz, at 1.45V;But What I am really want to know about it the both the “safe” and “generally stable” cup temperatures, a table of temps from below 20ºC to 80ºC, where the core goes up in smoke (well maybe not that), would be most helpful.