Can't use fast memory because of CPU speed?

This isn't me but is a poster on another forum. I have no clue about the answer to his question but figure that a bunch of you on here will know so ???

I've posted a link to this thread in the original topic at http://www.anglersnet.co.uk/ubb/ultimatebb.php?ubb=get_topic;f=6;t=008387

 

Basic scoop is this - a 3000+ is technically rated to run at 333mhz on virtually any MoBo with a 166mmhz chipset, however, Athlon's in general and Bartons (the one you are talking about) in particular are notoriously under-rated. That CPU will run on virtually any NVidia dual channel board and most VIA dual channel boards without breaking a sweat, provide the memory is good memory (preferably a matched pair). Soyo Boards are the exception to this as a 400mhz (2x200) Soyo board will only take PC 2700.

Barton 2500+ CPU's (333mz) - (kid brother of 3000+'s and 3200+'s) will run at 400 mhz without a hiccup too. In fact, they're about the best buy around for $80-85. The great chip these days is the 45W mobile Athlon 2600+ which is only supposed to run at 266MHZ - guess what - 400mhz right out of the box. I'm running my first one on a dual channel board at 12x200 which is faster than the Athlon 3200+ (a true 400mhz CPU). Idles at about 39C too.

I think your friend might have gotten piked because even though he got 400mhz memory, its probably not a matched pair and probably not going to run at the latency needed to take advantage of his "potential horsepower ". The exception to this is Samsung, but other than that - it better be real high end memory if he want's to give it a go.

 

its probably not a matched pair

How 'matched' does the memory need to be? Same specs, same brand, same color, ???

And since, at a guess, Dan doesn't know much more than I do about hardware, could you and Christer say the same stuff again but in English?

I got confused.

 

Thats a great question to which I have no answer - not what your friend wants to hear but "it all depends ". I'm sure someone has a perfectly logical scientific explanation but theory and reality don't always follow the same path. I've found some motherboards are more forgiving than others but will share an experience with you.

Last November I built a machine for myself using a DFI NVidia dual channel MoBo teamed with a 2500+ Barton and my game plan all along was to overclock it. I bought a matched pair (2x512) of Corsair XMS Xtreme low latency sticks (2-2-2-5 T1). Mounted the CPU, put everything together and after a little voltage bump to the processor, I was up and running - nice & stable - 11.5x200 just like a 3200+. The following week one of my clients brought a machine over for repair and saw my new pride and joy - his comment, "build me one just like it without all the lights ". Not a problem I thought - I had a couple of identical cases and a couple more 2500+ Bartons of the same stepping, plenty of other components - the only thing I didn't have was the same memory. However - I did have two more Corsair XMS Xtreme 512MB PC3200 sticks with platinum heat sinks that were rated at 2-2-2-5 T1 ...... only difference (so I though) was that they weren't a matched pair even though I bought them at the same time. I put a machine together and after two days of trying to figure out the memory settings, I couldn't get em'. Now my customer/friend was getting anxious and impatient and I was falling behind schedule - NewEgg was out of stock on the exact match so I bought a matched pair of their Pro Series Xtreme low latency (2-3-2-5 T1) and have it overnighted. Nice stuff - LED's and all, even a bit more expensive. Figured I'm out of the woods but wait, its still a no go - can't get that sucker to stabalize no matter what. Thinking that it no longer makes sense to focus solely on memory, I pull the **** thing apart and change out motherboards - still no go - change CPU's - still no go. By now, I've tried every trick I know and this is fast becoming an obsession - I've already lost my shirt on the deal but, admit defeat? - no way. Fortunately, NewEgg has memory back in stock and another overnight order is placed. My customer is becoming more client and less friend with each passing day and we're only talking a few days here. So what happened? Popped the "just delivered" memory in and haven't looked back since. I used the other memory in ABIT and Gigabyte dual channel boards and had no problems - go figure?

Now, if someone has a technical opinion I'm all ears - I too, would like to know how "matched" the stuff needs to be.

 

I hope your friend (turned client) has calmed down. Seems to me like they probably didn't realise what you were trying to do and the work involved.

I agree with you, it's very specific to particular hardware configurations as to whether matched pair RAM works as intended. Only thing that worries me is how stable these configurations are down the track when there has been "electronic wear" and changes in tolerances in some of these critical component configurations that seem to work, or, don't.

 

It was (is) actually client turned friend - referral whom I had never met before a year ago. IT Director at a local college originally sent him my way to fix a problem machine. And, he knew exactly what I was doing - however, neither of us anticipated the DRAM debacle. Looking back, I wouldn't trade the experience for anything and he has since purchased 2 more machines - one for college son and another for daughter in NYC - (MachSpeed MoBo's with 2500+'s)

I totally agree with you re: changes in tolerances in some of these critical component configurations and stability down the track - the primary objective is stability and long term reliability without pushing things beyond known "acceptable" and "safe" tolerances - no hiccups - no surprises - not today, tomorrow, next year or the year after. Its one thing to build something for yourself, but when one puts together a box for someone else, it better be close to "bullet proof ".

 

I don't know where the whole "matched memory" thing started in this thread. It's my understanding that the memory he got is all PC3200 (400Mhz).

As such, I think your friend should be congratulated. Buying PC2700 (333Mhz) memory at this point in the game is a bit too conservative. Whenever this person has a system that does run at a 200Mhz FSB, this memory should be up to the job. And I find it hard to believe that there would be an XP3000+ out there that would not easily run at the 200 FSB. Of course, the mainboard is a factor as well.

Unless you're mixing ram, I recommend always buying PC3200 as a future investment even if only PC2100 is needed. And I'm finding that PC2100 is now more expensive than PC3200 - I'm talking quality RAM here.

So I don't think there's any reason to be peeved here.

Rockster, you're obviously in touch with the Athlon scene. I toyed with the idea of getting a "mobile" but I have a 2600+ Tbred running at 11.5x200 so my money would better be spent on a different upgrade - but from all the incredible stories I hear, it sure is tempting.

Gary

 

Rockster2U, et all,

It could be Clock Timing, or Power supply instability. These things are now operating I believe in the nanosecond clock timing range. My past experience with nanosecond operated devices are they need extremely stable Voltages, and the Manufacturers tolerances must also be of a tighter tolerance. So It appears that the ones you inserted that drove you "Buggy" may not have had the tolerances that the specific circuit required. The ones you later inserted that did work showed that the Power Supply was not the fault.

BTW one can see these timing pulses with a Good Expensive Synchroscope, and actually view the instability/stability, plus all the exteraneous noise on the baseline that the power supply may not filter out.

Here's a website (for the Tecnical minded) that shows some Timing Diagrams:
http://www.dewassoc.com/performance/memory/memory_speeds.htm

Hope this helps.

 

Don't think a Synchroscope is going to make my shopping list but do appreciate your comments. Technically, you are way over my head and have probably forgotten more than I'll ever know. I skipped some of the blood & guts but had tried a couple of different Power Supplies as well. Started with a 600Watt and backed down to a 550W with tighter tolerances and almost the same amperage. Practically lived on Adrian's RojakPot Bios pages and reset CMOS so many times after trying different memory timings that I considered making a jumper with an extender attachment (nowhere near the battery - buried way at the bottom most corner of the board). Tried a host of different voltage steps/combinations in VCore as well as memory. Didn't mess with agp voltage but that wasn't a factor anyway. Regardless - learned just how little I really knew - (machine humbles man) - and I've done some "couldn't be done according to the mfg" configurations before.

Now, if you and a Synchroscope only lived a bit closer .......
Hehehe .....

Back to Newt's buddy - heck, have him try a manual setting of something like 11x200 and see what happens - isn't going to hurt anything as long as he doesn't start pushing voltages - that should give him the same cpu speed, but with a 400mhz bus. Then he can set memory to auto and find out if it works. His CPU should handle 12x200 or more without a problem - the only question is the MoBo & the memory. If it won't boot - reset CMOS. Nothing ventured, nothing gained.

 

irdreed

Excellent resource. Thanks.

Even more here but now requires a subscription to get to the real nitty gritty. Used to be free, but has been such a resource for me, I didn't hesitate to pony up when they went paid site. Saved my butt on more than a few occassions.

 

Rockster2U,
Thanks, but most of my explanation was from past experience, having the fun of having worked on such devices, with their nanosecond clocks and aligning them, using those good Scopes I had mentioned.
Sorry for being so technical, (Reminds of the saying, "Oh no you did exactly as I asked!! ")

That site I still have bookmarked. I've used them previously also for many queries..... so thanks for the update on them being a subscription site now.