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RAM timing doesn't meet spec


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I'm on my second pair of TwinX 1024 3200XLPT DIMMs. I started to get lots of BSODs and inability to run Prime95 in 10/2005 when my first pair was about four months old. Corsair graciously exchanged them for a new pair, and at "auto" timings (2.5-3-3-5), 1T, the computer worked flawlessly. When the new, current, pair of DIMMs was about 5 months old, I started getting the same problems --BSODs from PAGE_FAULT_etc, mostly, but also a few others.

At this point in time, I can run at CAS 2.5/command rate 2T or I can run at CAS 3/1T. Trying to run at 2.5-3-3-5/1T errors Prime95 within a couple of minutes. At 3-3-3-5/1T or at 2.5-3-3-5/2T, I can run Prime95 for 12+ hours without an error. Vdimm has been set at 2.9 all along, never less or more since this second set of DIMMs was new.

 

One stick of Corsair VS512MB400 will run at CAS 2.5/1T (don't have two sticks to test dual-channel with ValueSelect)

 

I'd love to be able to run at the spec of 2-2-2-5/1T for which I paid a premium price, but I can't even get close. Is there anything else to try before declaring this set of TwinX faulty?

 

System:

1 - A8N-SLI Premium -- NOTHING OC'd and MBM5 shows all voltages within spec --i.e., within ±3%, specifically, 3.28, 4.97, and 12.08V. Latest non-beta BIOS

2 - Athlon 64 3500+ (rev E) at default Vcore of 1.39V

3 - Antec TPII 550

4 - Single Radeon X800XL

5 - Antec P180 with all 4 120mm fans running (case temp never >30° and CPU never >38°, on an XP120 with Panaflo controlled by Asus QFan)

5 - 74GB Raptor and 300GB Seagate SATA

6 - two optical drives

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Command Rate is not really a memory setting and would be dependant on the make and model of MB and PSU and the specific CPU you have installed. You might look this setting up on http://www.rojakpot.com and get a better explanation.

 

Please load setup/optimized defaults and then set the Dim Voltage to 2.75 volts and then set the timings manually to the tested settings for the specific module you have, XMS3200XL Cass 2-2-2-5 and then test the module/'s one at a time with www.memtest.org! If you still get errors, please follow the link in my signature “I think I have a bad part!” and we will be happy to replace them or it! However, if you get errors with both modules that would suggest some other problem and I would test them in another system or MB to be sure.

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Thanks. I was hoping you wouldn't want me to test the DIMMs individually, because getting the one in slot A1 in and out with the CPU heatsink installed is a really frustrating chore. But I'll do that and post the results if it's mandatory.

 

I'm really surprised to hear that Command Rate is "not a memory setting." That raises several questions. In my BIOS, the only access to it is under the "DRAM Configuration" menu, and it's labeled "1T/2T timing." How could this not be classified a memory setting? Adrian Wong on Rojakpot.com also lists it under his "Memory Subsystem" section. If it's not a memory setting, is it conceivable that supplying more voltage to the memory controller (in my case, in the CPU), could make it more stable? Shouldn't high-quality RAM, with only 2 sticks installed, always be able to run at 1T?

 

Thanks again.

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Shouldn't high-quality RAM, with only 2 sticks installed, always be able to run at 1T?

No, I would suggest you read what is actually being set with this setting.

 

Quick Review(from http://www.rojakpot.com)

This BIOS feature allows you to select the delay between the assertion of the Chip Select signal till the time the memory controller starts sending commands to the memory bank. The lower the value, the sooner the memory controller can send commands out to the activated memory bank.

 

When this feature is disabled, the memory controller will only insert a command delay of one clock cycle or 1T.

 

When this feature is enabled, the memory controller will insert a command delay of two clock cycles or 2T.

 

The Auto option allows the memory controller to use the memory module's SPD value for command delay.

 

If the SDRAM command delay is too long, it can reduce performance by unnecessarily preventing the memory controller from issuing the commands sooner.

 

However, if the SDRAM command delay is too short, the memory controller may not be able to translate the addresses in time and the "bad commands" that result will cause data loss and corruption.

 

It is recommended that you try disabling 2T Command for better memory performance. But if you face stability issues, enable this BIOS feature.

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No, I would suggest you read what is actually being set with this setting.

 

I did read it (thought I indicated that, if indirectly). I'm still confused, though, so I hope you can answer each of these questions rather than just one.

 

I've been under the impression that with but two sticks installed, the quality of the RAM is what determines if it can accept commands after only one cycle rather than having to wait for two cycles. I've never read of anyone using my mobo who can't run at 1T with RAM timings specified by the manufacturer. Virtually everything I've read states that unless the Command Rate is set to 1T, there may be a 5-10% decrease in memory benchmarks and that it's a bigger factor than CAS latency in determining performance. Is this not true? Isn't achieving stability at 1T pretty important?

 

For example, I've settled on CAS 3/1T rather than CAS 2.5/2T; both give stable operation, but isnt' performance significantly better with the CAS 3/1T option?

 

Shouldn't I be able to run XMS-3200XL on an A8N-SLI Premium with a good PSU at 2-2-2-5/1T?

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Q: I've been under the impression that with but two sticks installed; the quality of the RAM is what determines if it can accept commands after only one cycle rather than having to wait for two cycles. I've never read of anyone using my MOBO who can't run at 1T with RAM timings specified by the manufacturer. Virtually everything I've read states that unless the Command Rate is set to 1T, there may be a 5-10% decrease in memory benchmarks and that it's a bigger factor than CAS latency in determining performance. Is this not true? Isn't achieving stability at 1T pretty important?

 

A: No that’s not true at all, this is subject to the memory controller, and in the case of AMD64 since its in the CPU the specific core of CPU and the make and model of MB and the PSU you use will be the biggest factor. But to test; please test the modules one at a time at 1t to be sure. If they both run at 1T one up but not when in D/C then its probably not the memory.

 

Q: For example, I've settled on CAS 3/1T rather than CAS 2.5/2T; both give stable operation, but isn’t' performance significantly better with the CAS 3/1T option?

 

A: Its best to test the modules one at a time as suggested above and doing some benchmarks would be what I would suggest to find the best configuration for your system, no two configuration will be exactly the same!

Q: Shouldn't I be able to run XMS-3200XL on an A8N-SLI Premium with a good PSU at 2-2-2-5/1T?

 

A: Yes but what do you call a good PSU (PC Power & Cooling 850 Watt-SLI would be what I would call a Good PSU!), and what is the exact configuration and what Video cards are you using and what is the specific core and speed of your CPU?

 

 

Bottom Line: I have no problem replacing your or anyone's modules, but most times with this type of issue the PSU and specific core of CPU is the cause of problems at 1T. If you just want to get them replaced, please use the On Line RMA Request Form and we will be happy to replace them or it.

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A: Yes but what do you call a good PSU (PC Power & Cooling 850 Watt-SLI would be what I would call a Good PSU!), and what is the exact configuration and what Video cards are you using and what is the specific core and speed of your CPU?[/b]

All that information is in my original post and in my specifications. Nothing's overclocked. I don't have a PCP&C PSU, but I think that my Antec TPII 550 is a very good one, and it checks out perfectly on the motherboard's built-in voltmeters.

 

I ran Memtest86 on both sticks in dual channel at 2-2-2-5/1T, and I got 15 errors in two passes. Tonight, I'll remove one and report again when I have all the data you require.

 

BTW, I checked the BIOS listing again, and it's labeled "1T/2T Memory Timing," so I'm still having trouble getting my mind around the fact that Command Rate is "not a memory setting."

 

Thanks VERY much for taking the time to answer my questions in detail. I'm learning a lot here.

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There have several users on this forum have trouble with Antec PSU's and if I remember correctly if you have the HE Model it will have to be Version A03 of that PSU, but you can check with Antec to be sure its not a problem. And in most cases the type of problems I have seen with PSU's that will cause memory errors, you would not be able to see with a volt meter.

 

But I would test the modules one at a time with http://www.memtest.org to be sure one is not failing. And I would test with the command Rate set to Auto or 2t.

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There have several users on this forum have trouble with Antec PSU's and if I remember correctly if you have the HE Model it will have to be Version A03 of that PSU, but you can check with Antec to be sure its not a problem. And in most cases the type of problems I have seen with PSU's that will cause memory errors, you would not be able to see with a volt meter.

 

But I would test the modules one at a time with http://www.memtest.org to be sure one is not failing. And I would test with the command Rate set to Auto or 2t.

 

I'm very well aware of the problems with the Antec Neo HE. As I mentioned a few times, I do NOT have that PSU. I have a time-honored TruePower II 550W. You said that you'd call the PCP&C 850 a "good PSU." Wow, so would I! For $439, it damn well ought to be, but surely you don't mean to say that to run Corsair products at their specified timings, you need a $439 PSU, do you?

 

I'm testing the DIMMs individually with Memtest-86 ver 3.2, but I like to let that run overnight, so it will be >1 day before I can post the problems.

 

Thanks again. I appreciate your helping me through this even when it might not be the RAM that's faulty.

 

Ron

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Iam sorry but I think you are missing my point. I am not slamming Antec nor do I want to, its just the problems you have listed would also suggest a noisy or failing PSU as well. I have no problem replacing your modules if you just want to try that, but what you have posted might suggest some other problem. Even P.C. Power & Cooling could make a faulty PSU, just like we might have a failing module, so please test the modules one at a time with http://www.memtest.org to be sure one is not failing. And I would test with the command Rate set to Auto or 2t.

 

To submit an RMA request, please use the On Line RMA Request Form and we will be happy to replace them or it.

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I thoroughly agree with you that we don't want to replace modules unless we can get good documentation that one of them is bad. I'm suspicious of a bad DIMM because I've already been through this once and replacing the DIMMs once before took care of the problem. However, I do concur that just because new DIMMs cured it last time doesn't mean that there's not a problem with PSU or motherboard this time.

 

Unfortunately, I started with Memtest-86 3.2 which I'm now told is "worthless." With version 3.2, my first DIMM, installed singly in slot B1, went through 15 passes at 2-2-2-5/1T, 2.75v, without an error, but I guess I should go back and do that again with the latest version of Memtest. It will take a couple of days to do this stress testing, but I'll post results as soon as I have them.

 

Thanks again.

 

Ron

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Actually, Asus specifies B1 as the slot to use for single DIMMs, so that's how I did it. With the latest version of Memtest-86, each DIMM tested perfectly overnight at 2-2-2-5/1T. I know you suggested 2T, but I decided to really given them the acid test, and they passed.

I then reinstalled both simultaneously in dual-channel mode again to try to determine the timings that would not give errors. To start that process, I simply ran Memtest-86 again at the same very tight timings for a baseline, and it ran through 9 passes (over five hours) without a single error!!

Prime95 on the RAM-intensive setting has now been running in Windows for 50 minutes without an error, still at 2-2-2-5/1T.

 

In the process of testing, the DIMM that was originally in B1 ended up in A1 and vice versa, but I can't imagine that made a difference. As far-fetched as it seems, I'm guessing that the simple process of reseating the DIMMs stabilized things. The way DIMMs are latched into place, they can't come loose, and I NEVER would have thought that reseating them could make any difference. I'll have to leave the computer on overnight to be sure, but it seems that I'm now running stably at memory timings better than I ever dreamed of trying before.

Does this make any sense?? Could simply reseating a DIMM "cure" the instability I was seeing?

 

Ron

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Could simply reseating a DIMM "cure" the instability I was seeing?

Yes it could, and if you continue to have problems I would try them in slots A2 and B2 and see if it changes.

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No problems for now. Prime95 Torture Test continues to run, now at 2.2 hours, without a hiccup at Corsair timing specs of 2-2-2-5 and at 1T. These are timings that are faster than I've ever achieved on this machine . Still seems kind of miraculous to me, and it embarrasses me that I titled the thread as I did.

 

I live in Ohio, not near the ocean, and my problems occurred in the driest months of the year -- i.e., no reason to suspect corrosion. Since DIMM sockets totally prevent the RAM from coming loose, does the fact that the problems seem to have been resolved by reseating DIMMs imply a problem with the motherboard?

 

Ron

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Thanks, very much.

It's perfectly stable. Prime95 Torture Test ran for 14 hours without an error.

 

Getting a DIMM out of and back into slot A1 underneath an XP120 heatsink is very, very frustrating, but if you hadn't directed me to do that, then this problem would not have been solved until much later.

 

Ron

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