Memory timing issues

[novacthall]

I have an older machine that I'm working to squeeze just about every last ounce of power out of it that I can. Here are my specs:

AMD Athlon 64 X2 3800+ (Holy) Toledo @ 2.0GHz (stock)
2 GB (2x1GB) Corsair XMS 184-pin DDR400 (PC 3200) 2-3-3-6
ABIT AV8 Socket 939 Motherboard
PowerColor X1950Pro AGP 256MB
Windows XP Professional SP2

I'm taking a break from overclocking my processor, since my last runin with overclocking was only useful from the standpoint that I learned a lot from it. My old Athlon 64 3500+ is still running at stock speeds (inasmuch as it's no longer in the socket) and has been replaced by an X2 3800+ that I nabbed for $80. I will, at some point, try to get the new processor at least up to the clock speeds I had with the 3500 (2.2GHz), which I have read is possible. I have also read that 2.4GHz is easy for this chip with air cooling, and I may try that in the future.

But today, I'm puzzled by my RAM's behavior. I've noticed that the timings on my RAM, when I set my motherboard to auto-detect, consistently set to 3-3-3-8 at 166MHz. Given that I have DDR400 memory and not DDR333 memory, I went into the BIOS and set my tCL-tRCD-tRP-tRAS to match up with spec, and also set the speed to DDR400 (though many options, both higher and lower, were available to me). I saved my settings and exited the BIOS.

The systems POSTs fine, and gets just up to the Windows boot, but cannot initiate. There was an error that said that system files were missing and Windows could not be started, and it recommended that I try using the recovery console. Being a wily type of guy, I instead reset the DRAM to Auto, at which point the system boots just fine.

So is there something I am missing? Is setting RAM timings not as simple as just... well, setting your RAM timings?

 

[theprodigalrebel]

Did you set the voltage to the manufacturer spec?

 

[myocardia]

The new XMS requies 2.75v for 2-3-3-6-1T timings@ 200 Mhz.

 

[novacthall]

Both of you have touched on an aspect of DRAM configuration that had not crossed my mind. I can't say I didn't learn anything today, and for that I thank you.

I just checked my BIOS and the voltage control is in User Define mode (which I suspect was triggered when I first made my changes to the RAM timing), but the DRAM voltage was set to 2.65 V. I looked at my options for changing it, but my options are 2.6, 2.65, 2.7, and 2.8. The jump is odd to me, and it does not seem that there is anyplace I can input 2.75 as the voltage. I did not make any changes, since I wanted to ask about that here first.

Should I go with 2.8 V and overshoot the requirements slightly or will I likely get the results I'm after by setting to 2.7 V?

 

[MarcVenice]

most ram should operate at 0,1v below or above the stock voltage.

putting it at 2.8 won't hurt it for sure, so it's worth trying. I hope it fixes your problem, but I kind of doubt it, if your ram is stock at 2.75 then 2.65 should work too.

 

[novacthall]

Thanks for the reply, MarcVenice. I upped the voltage to 2.8 and tried the timings with 1T rate and got the same problem.

Just for grins, I set the voltage to auto and set the DRAM timing to "By SPD" at DDR400. That clocked me to 3-3-3-8, but the system seems stable. I'm going to try playing some games and see how that does.

Is that appreciably different from 2-3-3-6? I'm not getting ripped off, am I, or am I beating a dead horse? Would I get better speed results if I overclocked my CPU instead?

 

[CTho9305]

RMA it. Don't accept defective hardware.

 

[myocardia]

What's the exact model number of your RAM, including the version #? Some of Corsair's RAM runs one timing on an Intel system, and higher timings on AMD systems. Why do you think I never use Corsair?

 

[novacthall]

This is exactly what I ordered from NewEgg:
http://www.newegg.com/Product/Product.asp?Item=N82E16820145587

I can't seem to find the C2Pro on Corsair's website anymore.

I did not know that timings work differently on AMD and Intel systems. That's pretty sneaky. Since you don't use Corsair, what do you recommend? Would swapping out my RAM at this stage in the game really get me a faster system or am I better off saving the money for a later upgrade?

 

[theprodigalrebel]

I found the official spec sheet on their website: PDF
They don't specify recommended vdimm there so I think it SHOULD work on default voltage. Manufacturers always recommend a specific voltage if the modules need it to work at advertised spec.

My suggestion is to make a thread in their official forums before going for a RMA. The performance difference between 2-3-3-6 & 3-3-3-8 isn't really much but you SHOULD get what you paid for. I recommend you make a thread here in their official forums - from what I know, their 'RAM GUY' is quick to respond to any queries.

Good luck to you buddy!

BTW, do they work @ 2.5-3-3-6? I remember Newegg used to mention something like '2-3-3-6 for Intel, 2.5-3-3-6 for AMD' the last time I looked at Corsair's DDR400 memory up there.

If they don't work as advertised, you can RMA. But do check with Corsair's forums.

 

[Yellowbeard]

Novacthall, can you list all of your bios settings that relate to voltages, CPU, and memory? Also, have you tried clearing the CMOS and then setting your timings again manually and setting the RAM voltage to 2.8v. These modules are safe up to 2.9v so no worries there.

Also, what PSU are you using?

 

[Yellowbeard]

Oooops....forgot. Try testing each DIMM individually using Memtest with the CPU at stock settings, RAM voltage at 2.8v, and the timings set manually. Test each DIMM for 5-10 passes each.

Do you have the most recent bios for that MOBO? This board was moderately unstable for a while until ABIT came out with some bios updates.

If the RAM tests OK, you may get some help here: http://forum.abit-usa.com/index.php

 

[novacthall]

I am at work at the moment, Yellowbeard, but thank you for the suggestions. I will run the tests and get the information you request when I get home this evening.

I may be able to answer some of your questions off the top of my head, though.

Regarding clearing the CMOS, I have done that a few times in the last few weeks, actually. I had kind of a nasty run-in with overclocking that kinda-sorta putzed out my computer (I was getting all kinds of CRC errors, which is usually indicative, as I understand it, of bad memory, but I left Memtest86 running for about 8 hours on a Saturday with zero errors). So I reinstalled Windows, then realized it would be prudent to clear the CMOS, and did so. I should probably reinstall Windows again (since the CRC errors are probably still manifest in the Windows install of the pre-CMOS clear), but I'm planning a wedding right now, so my life is nine kinds of crazy. What can I say? I'm a glutton for punishment.

I will give it a clear when I get home and reset my timings, as you suggest. If I recall correctly, my motherboard allowed for voltages up to 2.8.

Regarding the PSU, I'm honestly not sure. For some reason the company and model elude me, but I know it's a 450 watt.

Regarding the BIOS, I do have the most recent revision. The video card I'm using now is an upgrade from an old X800 I had in there, and when I put in the X1950, I was getting all kinds of instability. I updated the BIOS and my pains went away. Also, the new(est, they no longer support this board) BIOS supports dual-cores, which is what I've got plugged in there now (also an upgrade).

Thanks again for all the help.

 

[Yellowbeard]

My wife works (and I have helped) her in the wedding industry for about 8 years now so, I feel yer pain.

Regardless of the issue here, if you find it's the RAM, we'll gladly replace it. According to the PDF, this memory has been tested on AMD platforms at CAS2 so it should do it as long as there is no other problem.

As for the much older AMD compatibility issue, right after AMD went to the integrated memory controller, there were some modules and ICs that did not like CAS2 when combined with those CPUs. However, this was not with socket 939s, and was attributable to the latency on the memory controller. This will not affect your system.

Let me know if I can help......with the puter that is.

 

[timzak]

Can you clarify: Have you had this RAM all along running at 2-3-3-6 1T? Did those timings stop working after the cpu upgrade? Have you tried 2-3-3-6 2T? Some motherboards can't run @ 1T @ 200Mhz and some memory can't run at 1T in pairs (only singles).

Don't be so quick to blame the RAM. Sometimes the motherboard cannot run RAM at its rated timings. That's why your answers to my first two questions are...ahem...Crucial. ;-)

 

[novacthall]

theprodigalrebel, I neglected your post earlier, and for that I apologize. Thank you for digging up the information.

theprodigalrebel
>>My suggestion is to make a thread in their official forums before going for a RMA.<<

I like that advice. I'm a huge proponent of fixing the problem myself (if I can, that is) before sending any equipment back to the manufacturer. I've browsed around the House of Help and it looks like an excellent resource. I happen to know, as well, that these boards can also be an excellent resource with many teachers, so I usually default to bouncing ideas off fellow ATers before jumping to any conclusions or taking risky actions.

>>BTW, do they work @ 2.5-3-3-6?<<

Now that I will need to check. I have a tendency to stick to integers when dealing with computers, so I'll bust out a decimal and see how it goes.

Yellowbeard
>>My wife works (and I have helped) her in the wedding industry for about 8 years now so, I feel yer pain.<<

It sure takes a special kind of crazy to enjoy this, let alone choose it as your profession! My beloved and I have our hands full working on our own wedding, and I can't imagine the pains (or drama!) of working on someone else's.

>>Regardless of the issue here, if you find it's the RAM, we'll gladly replace it. According to the PDF, this memory has been tested on AMD platforms at CAS2 so it should do it as long as there is no other problem.<<

That's what I thought. I seem to recall the spec sheets being very clear about the capabilities of the modules. However and that being the case, I tend to default to PICNIC error classifications than to genuine hardware defect.

I should also mention that there aren't technically any "issues", per se, with the RAM. I've been using it problem-free for over a year in this system, but have only recently become aware enough to understand RAM timings and the more intricate details.

>>Let me know if I can help......with the puter that is.<<

Thank you, I certainly will. Now, about your marriage-planning wife... (Kidding, we're three weeks away from the date, pretty much everything's already in place.)

timzak
>>Can you clarify: Have you had this RAM all along running at 2-3-3-6 1T?<<

I am happy to clarify. My suspicion is that the RAM has been running all along at 3-3-3-8 2T, which is what CPU-Z reported the first time I downloaded it about a month ago. I am unsure what speed the memory was running at, but I found that the automatic detection feature of my mobo was sandbagging just about everything.

>>Did those timings stop working after the cpu upgrade?<<

To my knowledge, they did not work before or after the upgrade. Only after I plopped in the "new" CPU did I get a nasty case of "If I can install a new processor, I can do ANYTHING!" syndrome and decided to take a stab at my RAM timings again.

>>Have you tried 2-3-3-6 2T? Some motherboards can't run @ 1T @ 200Mhz and some memory can't run at 1T in pairs (only singles). <<

I did not know that, and I have not yet tried 2T burst. I will give that a shot tonight.

>>Don't be so quick to blame the RAM. Sometimes the motherboard cannot run RAM at its rated timings. That's why your answers to my first two questions are...ahem...Crucial. ;-)<<

Make no mistakes about it: I'm a big proponent of PICNIC theory. I'm sure my RAM's just fine, I'm just betting that there's something I either have not yet fully educated myself on or have overlooked.

Those are some great questions, timzak. I'm an engineer, so I appreciate the logical thought processes.

 

[novacthall]

Okay, update time.

I sat down at my computer and decided that I would take the long way through the issue. Basically, I resolved to change one issue at a time to determine what the problematic parameter is (Six Sigma black belts are shaking their heads right about now).

First, I started with setting my command rate to 1T instead of auto. Exit BIOS, POST okay, Windows immediately blue screens before the desktop, black screens, and then kicks me back to the POST.

Hmmm.

So I set the command rate to 2T, and then proceed to set, across many reboots, all of the remaining DRAM settings to specification. Each boot is successful.

Right now, I'm writing you from a computer whose DRAM is configured to every specification except that my command timing is 2T instead of 1T. Honestly, that doesn't bother me in the least, but I have no clue what that means. I've read that generally 1T is used for performance and 2T is used for stability, but is that necessarily accurate? Is it possible that my motherboard simply doesn't support the 1T timing. Does this tie into Yellowbeard's earlier comment regarding the AV8 being a little wonky until the BIOS was revised? Perhaps they couldn't get this piece to fall into place?

 

[lopri]

Could be the motherboard, memory controller (which resides in the CPU), or the memory. (in no particular order) See if you can run 1T with one stick at a time. If successful, you can at least eliminate memory as the culprit.

P.S. Yellowbeard, did you read my PM? :frown:

 

[Yellowbeard]

Command rate is a chipset function. If the machine won't run 1T and the memory tests OK with Memtest at 2T, the memory is not likely the culprit.

 

[timzak]

Originally posted by: lopri
See if you can run 1T with one stick at a time. If successful, you can at least eliminate memory as the culprit.

Not necessarily true. I have a pair of 512MB DDR400 modules that are rated 1T singly, and 2T if used in pairs. Corsair XMS3200c2 (if my memory serves me well).

 

[Yellowbeard]

Originally posted by: timzak

Originally posted by: lopri
See if you can run 1T with one stick at a time. If successful, you can at least eliminate memory as the culprit.

Not necessarily true. I have a pair of 512MB DDR400 modules that are rated 1T singly, and 2T if used in pairs. Corsair XMS3200c2 (if my memory serves me well).

I think what lopri meant was that the memory is not defective per se if it will run in this fashion. Since command rate is a chipset function and not a memory function, the memory will not have multiple ratings for command rate.

Also, I am not aware of Corsair ever rating any PC3200C2 memory with any command rate spex, much less different command rates for singles vs pairs. Did you get this info from Corsair?

 

[timzak]

Originally posted by: Yellowbeard

Originally posted by: timzak

Originally posted by: lopri
See if you can run 1T with one stick at a time. If successful, you can at least eliminate memory as the culprit.

Not necessarily true. I have a pair of 512MB DDR400 modules that are rated 1T singly, and 2T if used in pairs. Corsair XMS3200c2 (if my memory serves me well).

I think what lopri meant was that the memory is not defective per se if it will run in this fashion. Since command rate is a chipset function and not a memory function, the memory will not have multiple ratings for command rate.

Also, I am not aware of Corsair ever rating any PC3200C2 memory with any command rate spex, much less different command rates for singles vs pairs. Did you get this info from Corsair?

I recall reading about it on a leaflet that came with my ram. I think I also saw it on a .pdf on their website. The memory is 2-3 years old now, so that pdf file may or may not exist anymore.

Or maybe I have defective memory.

 

[novacthall]

An update, for those of you who still care.

At DDR400, I'm running my memory at 2-3-3-6 2T timing. All the rest of my timings are at the lowest possible settings. System performance is fast, though whether it is faster than before by an appreciable amount, I cannot honestly say. The important thing, for me, is that I've learned the minute machinations of my memory and I enjoyed the learning process.

Perhaps completely unrelated: I'm getting oddly low frame rates in Terokkar Forest in World of Warcraft, to the tune of low teens. Everywhere else in the world is usually 30+ or 40+ in extremely busy areas. I'm not spending as much time out there anymore, though, so it's not as much of a concern.

Since playing with my RAM timings, I figured I would take another stab at overclocking my processor. I hope to write up a "lessons learned" and post it on the forum, for any other newbies who could benefit from my mistakes. I bumped my processor a nudge, lowering my multiplier so that I wouldn't run into any problems, and making sure my voltages were in order, I saved and exited my BIOS. Long beeps and a black screen greeted me. I reset my CMOS (I'm starting to feel like Agent K from "Men in Black"), set my memory timings back to the optimized setting, and did some more homework.

In fiddling around with my RAM timing, I became aware of the fact that my RAM speed was directly tied to my processor speed! How could I have overlooked this? So I way underclocked my RAM, stocked my CPU, and checked the RAM operating frequency. Reboot, bump up the CPU a few MHz and would you look at that: the RAM speed went up incrementally. Through the wonders of mathematics, I determined that operating my CPU at 240MHz x 10 = 2.4GHz on the CPU and at DDR333, lands me right around 200MHz (if I recall correctly). Stability and temperatures are very encouraging, and I haven't even altered my voltages.

I suppose the next question would be, going forward, am I optimized? Now that I can fiddle around with my BIOS without having to reset the CMOS every time I make some boneheaded error (due to the decreased number of boneheaded errors, thankfully), what steps can I take to further optimize my system, or should I just sit tight and enjoy what I've got?

Thanks again to everyone who participated in this topic. I learned much from this.

 

[zagood]

Try this.

Loosen the timings to 3.3.3.8 and run the memory at DDR400 (or whatever 1:1 is on your BIOS). Leave it at 2T. Also up the RAM voltage a little bit. That memory should handle that overclock. It'll be faster at 240mhz/3.3.3.8 than running at 5:6 at 2.3.3.6.

-z

 

[novacthall]

Thanks for the tip, zagood. I kicked up my voltage when I got home last night, loosened up the timings a bit, and upped the DDR frequency to DDR400. When I rebooted, I got the long beeps and no POST. Should I try setting the speed to DDR400 and leaving all the timings for the motherboard to sort out? I had to reset my CMOS again last night, but by now I've gotten pretty quick at redoing my overclock.

As a purely academic curiosity: how do you know what settings will work and will not work? Is it all down to trial and error or is there some greater underlying logic I'm overlooking?