T42 memory compatibility

[Jodan]

My T42 has one stick of Elpida 512k RAM. I want to add another, and other brands are much cheaper. Are there compatibility problems as long as I get PC2700, 333MHz, 200 pin, SODIMM, non parity SDRAM?

The RAM has to be ordered, and the man says no money back if it doesn't work. He also mentions that it can be risky. WDYT? Tx!

[FTC]

Hi, In general you should not find problems. Mostly any DDR PC2700 or PC3200 'standard' SODIMM will work. Once this is said, of course cheaper manufacturers tend to build products with less quality...

My suggestion is that you get a PC3200 SODIMM. Even if it will stoll work at 333Mhz (166 Double rate), it is more likely that it will be CAS2 or CAS2.5 at this lower speed, plus it is a better investment for the future... and in today's crazy market the fster modules are some times cheaper than the slower ones!.

[dr_st]

My suggestion is that you get a PC3200 SODIMM. Even if it will stoll work at 333Mhz (166 Double rate), it is more likely that it will be CAS2 or CAS2.5 at this lower speed, plus it is a better investment for the future... and in today's crazy market the fster modules are some times cheaper than the slower ones!.

PC2700 is CAS2.5 at 333MHz. PC3200 might be CAS2, but of course it will still be running at CAS2.5 when matched with the PC2700 model. However I agree with you that int the future it may turn useful (like in an AMD-based notebook that can run PC3200 at 400MHz).

[Jodan]

The two types of RAM I can get are: A-Data and Kingmax:

AD512333N A-Data, 512 MB SODDR, 333 MHz, notebook
AD512333N2 A-Data, 512 MB SODDR, 333 MHz, (32*16), (notebook)
512M PC333 A-Data-SO-DIMM 16IC 32Mx8 Life-time
512M PC333 Kingmax-SO-DIMM 8IC 32Mx8 Life-Time

Any comments on those brands?

[FTC]

PC2700 is CAS2.5 at 333MHz.

Well, this is not my understanding. DDR PC2700 just implies that the memory runs at 166 (x2 since DDR) MHz, being 64 bits wide (8 bytes) it makes 333x8=2664 MB/sec peak throuput which (rounded) accounts for the 2700.

I've seen PC133 (SDR) CAS2 or CAS3, and PC2100 / 2700 sold as CAS2, CAS2.5 and/or CAS3. It *may be* that the standard for DDR specifies a minimum CAS latency (I have not verified this point), in which case you may be right, but even in that case my suggestion would make sense as a mean to ensure avoiding manufacturers not fully compliant with the standard.

[dr_st]

PC2700 is CAS2.5 at 333MHz.

Well, this is not my understanding.

OK, I'll phrase it better.

Every stick of SODIMM PC2700 I have seen was CAS 2.5. Others may exist, but if so, they are probably very scarce.

Edit: here, I gathered some stats:

Newegg DDR333 SO-DIMMs

Out of th 53 listed - 37 are CAS 2.5, 2 are CAS2, 1 is CAS3, 13 don't report CAS Latency.

[NUKE40]

I was accidentally sent a PC3200 Corsair SODIMM for my T40 instead of a SMART PC2700. Will the PC3200 work reliably in the T40? Is Corsair as good as SMART?

Thanks,

Ted

[dr_st]

How come people "accidentally" get sent faster RAM from a better manufacturer?

(I hope this answers your question)

P.S. There is a rather small chance of compatibility issues. No real way of knowing except trying and seeing.

[NUKE40]

The Corsair PC3200 is from it's ValueSelect line while the Smart Modular PC2700 seems to be from the standard line. The Smart Modular is going for about $30 more than the Corsair online. Do you still think that I am better off with the Corsair PC3200 SODIMM for the T40 than the Smart Modular? I can probably exchange it.

Thanks,

Ted

[dr_st]

A RAM stick is a RAM stick. If it works and isn't faulty, you'll never feel the difference either way. Especially in laptops, where there isn't the option to overclock RAM or tighten its timings.

[NUKE40]

Is the 250mb PC2100 that I already have in my T40 likely to work more smoothly with the 1 GB PC2700 memory than the 1 GB PC3200 memory? Or doesn't it matter if it passes a MEMTEST+ test? Will having the PC2100 in there slow down the PC3200 memory? (The last question has probably been answered elsewhere.)

Thanks,

Ted

[dr_st]

It's really simple. T42 is used to run RAM at PC2700 speeds. Putting a faster stick in it (PC3200) will merely cause the faster stick to downclock to PC2700.

But putting a slower stick (PC2100) might have one of two effects - either it will cause the PC2700 to downclock itself to PC2100, which means your RAM will be running slower than optimal, or it may try to force the PC2100 stick to work at PC2700, which almost surely isn't going to work, and the PC might not boot or be highly unstable.

So, no, do not put the PC2100 in the T42.

[NUKE40]

Even though this thread is titled "T42 memory compatibility" my computer is actually a T40 with a standard memory of PC2100 (@ 266 mhz) as compared with the T42 with a standard memory of PC2700 (@ 333 mhz). However, it does use the Intel 855i chipset with a front side bus of 400 like the T42. In that case would the base PC2100 256 mb SODIMM slow down my memory if I can theoretically get to 400 mhz or am I already limited to 266 mhz?

I'd rather keep the extra 256 mb unless there is some reason (performance or reliability reduction) to remove it.

Thanks,

Ted

[dr_st]

Oh, sorry, but I thought we talked about it already. Anyway, the chipset can run memory up to 333MHz, it cannot do 400MHz. So the maximum difference you can expect is between PC2100 and PC2700.

As for compatibility, you might need to be a bit more careful here. There is a chance that some PC3200 RAM may not work smooth at PC2100 speeds. Probably will, but the risk is a bit greated, because of the bigger difference in specs.