Help with Mismatched RAM speeds
 

Hi,

I'm having some trouble installing a new RAM chip I bought. What irks me about my trouble is that I was anal about making sure I got a chip that was compatible, and now it seems I'm having trouble with it.

I have the ASUS P4S800-MX motherboard, and
I bought a Kingston Value Ram 512MB DDR PC3200 CL3 184-pin DIMM chip

The new chip is technically faster than my current (non-Kingston) one, but the 512mb size matches. Note: I bought a faster chip because it is on sale at half price (CDN $50); all other chip speeds are regular price.

I looked in the mobo user's manual, and it only says to install DDR chips that are 184-pin and it lists the sizes that work in the slots. It says absolutely nothing about RAM speeds.

The mobo has only two slots, so I was sure to get the 512mb chip to essentially "fill out" the system to 1gb of RAM, knowing full well that I'd have to replace one or both if I wanted to go higher than 1gb.

Can anyone shed some light on my situation? It seems I've run into some serious system instability: I tried to reintall Windows because I've been having trouble with it to begin with, with a .dll error every time I restart the OS. I noticed some instability when running the new chip, but it did start Windows and a diagnostic program said the chip was installed and all seemed dandy, but I started getting some program errors.

I went straight to a reinstall, thinking that it was a collection of factors that may have caused the instability, rather than JUST the new hardware. However, when the Windows installation was commencing, it kept coming up with errors as it was having trouble installing some of the files and they had to be skipped. This happened a number of times. Can RAM problems cause this?

I have since removed the new chip and now I'm trying to recover my system with the original chip only. Hopefully I can at least get back to where I started, but this still leaves me holding the bag: will I be able to get this chip to work somehow, or will I need to exchange it with a chip that has the exact same capacity and speed as the original one?

Any help would be greatly appreciated... All I wanted was a smoothly running system!

UPDATE: it seems that having removed the new chip also removed the problem of Windows setup not being able to install certain files. So far, so good... my fingers are crossed. It does seem that the new chip was causing this problem... but is there a way to get the damned thing to work?

Do you know the FSB speed of your motherboard?

Also, try running MemTest86 (http://www.memtest86.com/#download0)

Switch their positions, or try the new DIMM by itself. I can't speak to that board but some controllers detect timing based on one DIMM. If yours decided you had faster RAM then it could push the old, slow DIMM too quickly.

Check your BIOS timings with just the old DIMM and then with the new DIMM installed. If there's a difference with both installed then you may need to force it back to the slower rate manually.

Instead of booting and testing with your live system, try an alternate HD with a basic install. Any old thing you don't care about.

Best first attempt is with a memtest cd/floppy. Make one before you tear down again and let it make sure things look okay before subjecting your jewels to what may be unstable underpinnings.

Its just a general rule of mine that all the RAM in a system has to be uniform. Same manufacturer, same speed, same size, same read time, same age, and if possible, same batch. Each variation opens another potential problem and it seems like you've set yourself up for a lot of that.

Go back and buy another stick just like the one you just got and replace your old one.

Hal, Matched RAM does make for the simplest install, but I've found it's almost always possible to make mismatches work together. The exceptions are caused by motherboards with poor detection code or a lack of manual configuration.

Hal is exactly right. Same speed ram should work fine with each other, but in most cases, they don't. After being burnt multiple times, I will never, EVER buy ram that isn't the exact same brand, same speed, same freaking size out of the same package if I can help it. As a matter of fact, my next PC will feature a single 2 GB ram chip if I can find one. Crash to desktops in games, .dll errors, installation errors, VIRUS SCAN errors, blue screens of death, no boots, the list goes on and on. The ram is fine, it simply hates working with another brand.

FSB is 800MHz, plus it can do 533 and 400, apparently.

Another update: I managed to get my Windows up and running again, but ONLY when I removed the new chip...

Cyrnel, you idea for switching positions of the chips is worth a try. Do motherboards have some priority settings towards socket 1 over socket 2? I'm not going to try reinstalling Windows again now that it works right this time, instead I'll just plug around with the chips for a bit. If I can't get the new chip to work, I will exchange it for a chip that matches my original chip's speed. I can get a generic brand name K-Byte for $75. Not as good as $50, but at least I won't have to muck around with a rebate form.

No, not settings for which socket supplies the trusted timing, if that's what you mean. A detection routine may pay attention to one or another though and so be thrown off if there are DIMMs of different capabilities installed. Requiring like DIMMs certainly makes their testing efforts simpler. :rolleyes:

BIOS memory detection code varies in quality. Most of us have seen instances where memory that meets spec fails to work reliably. It isn't always the DIMM's fault. Sometimes the BIOS author or memory controller just pushes those ratings too far. Sometimes the SPD chip actually has faulty timing values. Sometimes the BIOS doesn't do the math correctly when matching SPD values with other variables it's dealing with. The fewer variables the better, but once you know what affects compatibility you can usually make anything work.

If nothing else, at least try moving the memory around between sockets and trying the new DIMM by itself. There's always the chance the new DIMM is faulty.

Inside the bios manually set the ram speed to the slower of the 2 rams speeds, it may be running at 400 MHz when the slower can’t run that fast.

Okay, tell me what you think of this:

cyrnel, I tried what you suggested and I switched the DIMMs. When I took out my original DIMM (which was supposed to be 2700) it had a sticker on it that says its 3200!! Despite what the diagnostic said, it actually matches my new chip in specs. Regardless, I switched their positions and it has thus far been okay. The diagnostic program I use (PC Wizard) says that they are indeed the same spec. Things are running great now!

I want to thank everyone for your help.

Great it's working now!

You'll find those PC/DDRxxxx names have become largely marketing tools with some distant connection to reality. Each chip has its own limits. The DIMM SPD values provide some clue, but the way manufacturers pick parts to fill orders you can only be certain by testing the stuff.

Download and burn a copy of memtest and give it a whirl overnight. Nothing else you do on your system will exercise and evaluate the memory as well.

Cyrnel...you are the shit!! I've come to TFComputers asking questions before and you've got me out of jams at least twice before. Earlier today I was on the phone with Baraka_Guru and when he told me his problem I said "go on TFP and Cyrnel will probably answer within 24 hours"

!

Awesome. Thanks again Cyrnel. You deserve some kind of award.

Thanks aberkok. I don't know if I'm batting 500 yet. Answering this stuff remotely is hit or miss. I think many people here - lurkers or otherwise - can and do answer things but some answers just fit or sound better for a given question. But hey, if I get to be board pedant for the day... :D

BTW, swapping DIMMs is the easy version of setting timing to the less capable of the two, like Dilbert and I mentioned in other posts. If BG checks the BIOS it's likely set to what it was with the old DIMM alone. Can't be sure without reading the SPD chip data but my guess is that something in the new one's made the board try timing that wasn't compatible.

Another small advantage to swapping is that you won't run into the problem again should you reset the BIOS.

Timing can be one of the more vexing box assembly gotchas. Those PC/DDRxxxx names are a huge generalization about the capabilities of a given stick of memory. BIOS coders often take shortcuts, support calls cost vendors lots of money, hence the popularity of matched pairs.