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Corsair TwinX 2048 C2PT, X2 4800+ and A8N-SLI Premium

Megatomic

Megatomic

Lifer
I've been hammering away at this issue for a week now and I'm no closer to resolution. So, maybe you guys can help me decide what to do.

Backstory: I've been overclocking for years, it was fun. But I'm busier now than I used to be and I don't have the time or inclination to mess with risks and quirks of an overclocked system anymore. So, I sold my budget parts and bought some high end stuff hoping to get top tier performance without overclocking. My choice in parts:

ASUS A8N-SLI Premium
AMD X2 4800+
Corsair TwinX 2048 PC3200 C2PT

I'm happy with the mobo and the CPU but the RAM is disappointing me. I can't run it at CAS2 as advertised on my system even with nothing overclocked on a clean install of WinXP Pro. I can overclock it while on CAS2.5, but CAS2 leaves my system unstable (crashes in Q4). When I run dual instances of Prime95 with the memory on CAS2 I get a failure in one of the instances within minutes of starting the test.

I've tried upping and lowering DIMM voltage and that doesn't help. I've raised and lowered every voltage as a matter of fact and none helped. I've got plenty of power so the system's not starving for voltage anywhere (SmartPower II 500W). Temps. are very reasonable (35C and 31C idle, 51C and 39C loaded) so that can't be the problem either. I've used the last two official BIOS versions as well as the newest beta BIOS and that didn't help either.

So my dilemma is this: should I just go ahead and sell off my high end RAM and buy some lesser RAM (still 2GB) and recoup some money I wasted? Or is there another option I can try to fix my situation with my current hardware? I'll listen to any suggestion other than "just overclock at CAS2.5", it's the principle of the situation that's bothering me here, not performance. Remember, I bought high end stuff so I wouldn't have to overclock anymore.

Thanks for reading and thanks even more for any help you guys can give me. :beer:
 
Have you tried different slots? Memtest86 testing to see if it's really the ram buggin? 2.8 volts?

I beleive that ram is rated 2-3-2-8 or 2-3-3-8 right.. so it should run it unless defective.

I wish I had that board to give more advice but that's all I can think to try.
 
No..just the limitation of the C2PT. I too am disappointed by these. They only run CAS 2 for Intel. AMD is 2.5. Plus, they don't OC for crap!
 
Zebo, the advertised timings are 2-3-3-6 at 2.75V. I did try them in the other set of slots with the same results. And I've ran the Vdimm up to 2.9V with no luck. One thing I haven't tried is running with just one stick installed at a time. Memtest86+ v 1.65 showed 2 failures in test 8 on the fifth pass. No other failure to note. The CPU passes all testing when CAS is 2.5 or if I run small FFT Prime95 on both cores with CAS at 2.0.

Sincity, you have the same results as I do with the same RAM on the ASUS SLI board eh? I'm sorry to hear that you've had the same problem as me, but I'm reassured to know that it's not just me or something I'm doing wrong. Is there a discussion going on somewhere you can point me to pertaining to this RAM and it's inabliity to run at CAS2 on AMD systems?

Thanks for posting guys. :thumbsup:
 
Originally posted by: Megatomic
Zebo, the advertised timings are 2-3-3-6 at 2.75V. I did try them in the other set of slots with the same results. And I've ran the Vdimm up to 2.9V with no luck. One thing I haven't tried is running with just one stick installed at a time. Memtest86+ v 1.65 showed 2 failures in test 8 on the fifth pass. No other failure to note. The CPU passes all testing when CAS is 2.5 or if I run small FFT Prime95 on both cores with CAS at 2.0.

Sincity, you have the same results as I do with the same RAM on the ASUS SLI board eh? I'm sorry to hear that you've had the same problem as me, but I'm reassured to know that it's not just me or something I'm doing wrong. Is there a discussion going on somewhere you can point me to pertaining to this RAM and it's inabliity to run at CAS2 on AMD systems?

Thanks for posting guys. :thumbsup:
Click to expand...

If you're getting errors in Memtest, it sounds like you have some bad/flaky Memory.

Also, Sincity is running an Abit MB, not an ASUS. This lends more support to your problem being a Memory or Memory Controller issue.

Didn't you say that you got things working in slots 2 & 4 earlier (other thread) ?


 
I proclaimed victory too early at that time wanderer27. It (prime torture test) ran longer but it eventually failed, too.

I may ask Corsair for a replacement set of memory. That's one more thing I can do before I give up on my dream.
 
Another test that's failed for me is to be able to run two concurrent super pi 32m tests. The version I use is the SSE3 enabled version. One test always fails with not convergent in sqr05 error. It is random, whichever test I push the start button second on fails, no matter if it's on core 0 or 1.

Could it be that it's my CPU that's bad? It was a brand new chip, still sealed in the box.
 
Megatomic: Per Corsair, these are advertised only to run at 2.5 on AMD systems. Funny thing is that I can run them at CAs 2.0 on my AMD XP! Anyway, RAMGUY, the Tech Support person at Corsair, would be happy to exchange or upgrade them (ugrades cost more).
 
If that's true (that Corsair advertises CAS2.5 for AMD) then I guess I got what I paid for. 😱

As to the Super Pi, I'm not going to worry about it too much. While I was sleeping (working nights this week) I ran 2x Prime95 while running 1x RTHDRIBL and 1x Super Pi mod 1.5 and nothing crashed. If that's not multitasking then nothing is. 🙂
 
Have you tried messing with some of the other RAM settings?

I have the A8N-E, it's running just fine with 4x256 Corsair 3200C2 at 2-3-3-6, stock vdimm (auto).

BUT I had to lower one of the other "T" settings from like 10T to 13T - otherwise it will not even POST. Also this board has a bug where if you have 4 dimms it defaults to 333mhz too... but I got it running at 400 @C2 no prob.
 
I haven't touched any of the timings aside from the normal 5. When I first set up the system, those timings were set by SPD, I then changed the others manually.
 
As others have alluded, on AMD you will do no better than 2.5 CAS. Futhermore, by reading the serial number off the side of the RAM stick, you should be able to determine which revision of RAM you have. With that info, go over the the RAMGuy/Corsair forums and track down the page which tells you which ICs are actually used in your C2PTs... Once you have that, you can track down how well the ram can be expected to overclock (i.e If they are Samsung TCCDs or Infineon etc etc etc) Lately, the C2 stuff they're producing doesn't overclock well. Further, most of the Corsair RAM out there doesn't like more voltage, unlike say, the OCZ stuff.

Either way, you might want to think about the *performance* difference (not SiSoft benchs...ACTUAL application framerates / load times etc) between your current C2 stuff at 2.5 CAS, and what you're going to buy. As per Zebo's other thread, its unlikely that you'd even notice the difference an extra $100 worth of RAM would give, especially on AMD.

Cheers,
A
 
Thanks for all that info keldog7. I'll check into which chips are on my memory stick on my next day off. Now let me ask you this: your system is similar to my own. If you were to run at DDR400, would you be able to run your memory at CAS2? Did you at any point try that configuration?
 
Well that is incorrect. C2 works fine on AMD, at least on my X2 4400+, A8N-E
(Corsair XMS 3200C2 (DDR400). It's 2 - 2.5 years old, pulled from another system (intel).

I'll post the full timings when I get home, but it works great and passes all tests with flying colors (including WoW and Quake4 for 1-2 hours at a time 🙂
 
Yeah, my RAM (in sig) will run CAS 2 at DDR400 (200 MHz)...in fact it will do better than that at CAS2 - 219 MHz is written all over the marketing of the stuff, and if it won't do it, they'll replace it. Anyway, I did a fair bit of research to see just how far I could push my Corsair stuff, and I think the fastest anyone had it going was 263 MHz. The timings had to be loosened, but again (as per Zebo's post), on AMD its mostly about throughput, not timings. Finally, if you're thinking of getting the same RAM as I bought (with all the flashing (i.e. useless) *bling*), keep in mind that the RAM is *tall* and might not fit well with a variety of heatsinks, motherboards etc. I posted links to some pics of my ram (beside a tape measure) installed on my board, if you want to check sizing. Hunt around my posts...the thread was something like "Corsair RAM will fit" or so.

walk2k: You may very well have the same RAM running at CAS 2...to be honest, I have a pair of C2PT on a A8NSLI in my basement (secondary machine), running at 2.5-3-3-7 1T. But the product documentation which came with *my* pair of sticks clearly stated that it was only rated for 2.5 on AMD boards. Maybe it has something to do with the fact that your chips are older? The older C2 used much better ICs, and are reputed to overclock wonderfully...whereas my newer version is a "dud" overclocker.

Cheers,
A
 
That's true, they are older and of course much smaller. These are 256MB sticks (x4), you're talking about 1GB chips, they larger chips may not tolerate faster timings.
CPU-Z SPD

The timings page in the BIOS (is rather lengthy...)
400mhz
2 (cas)
6T
3T
3T
10T
13T <-- if this is set lower than 13 the board will not POST (long beep, 2 short beeps)!
3T
3T
2T <-- command rate, errors with 1T, known bug supposdedly with this board when all 4 dimm slots are populated.
 
Hmm, it looks like CAS2.5 may just be harsh reality of the new Corsair DDR400 chips, especially in 1GB/stick configurations. I suppose I can live with that, all my apps (especially games) run well where it is now, and the entire machine is far superior to what I had a week ago.

walk2k, thanks for your feedback on the timings. One thing I can see that I have a little better than you is that I can run 1T command rate. You running at 2T is a product of using 4 DIMMs. That's a limitation of the AMD integrated memory controller.
 
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