[Mr. Bear]

I have purchased from a local vendor what their supplier has "claimed" to be G5 1.8/2.0GHz compatible DDR400 1GB module.

Installing the two 1GBx2 in Slot 1 pair and the original Apple 256MBx2 in Slot 2 pair and running Apple Hardware Test, I got the following -

DIMM0/J11 1024MB
PC2700-30330, DDR SDRAM
CL3:6.0,CL2.5:7.5
CE-0, M368L3223ETM-CCC
...

DIMM2/J13 256MB
PC3200-30330, DDR SDRAM
CL3:5.0,CL2.5:6.0,CL2:7.5
OB-3, NT256D64S88BIG-5T
...

Do I have PC2700 or PC3200 on the 1GB module? The system has been running fine for 3 days without any problem.

[Spliffdaddy]

Good question.

Those values you see are simply the information contained in the RAM module's 'spd' - serial presence detect. Generally, it lists the range of operation (timing, frequency) the RAM is capable of. Sometimes the motherboard's firmware will set operating parameters based on the information in the 'spd' - sometimes the firmware will ignore it completely...assuming that the expected hardware (the RAM, in this case) is the correct hardware.

Does the G5 use the information in the RAM's 'spd' ?

Another good question.

I don't know the answer, though.

Assuming the 'spd' info you're seeing is complete - I'd say that NO, the G5's firmware does not adjust operating parameters based on information contained in the RAM's 'spd'. If it did, one of two things would have happened:

1) The clockspeed of the RAM would be dropped to 166MHz (333MHz DDR, PC2700) in response to the 3rd party RAM's 'spd' info. I'm guessing your RAM is running at its normal 200MHz (400MHz DDR, PC3200).

or

2) The 3rd party RAM modules (or the entire bank that's affected, or perhaps ALL RAM banks, regardless) would be disabled and would not be counted as physical RAM.

Here's my opinion...

If the 'spd' information contained in 3rd party RAM modules does not match (IDENTICALLY) the 'spd' information contained on Apple's RAM modules - then it should not be sold as a 'Mac compatible' replacement/upgrade. If, in the future, Apple releases a firmware update that 'looks' at the information contained in the RAM's 'spd' - and abides by it - you're gonna have a problem with that 3rd party RAM. Chances are good that the RAM will no longer be 'allowed' to operate beyond its 'spd'-defined maximum clockspeed. The RAM will be disabled, I bet ya. This scenario played-out a few years ago with some G4 PowerMac models, if I'm not mistaken. Look for topics like "RAM disappears after fimmware update."

Most RAM modules will function reliably at speeds higher than the module's factory rating. It's almost expected that PC2700 RAM would still be OK at PC3200 speeds. Sometimes the only difference between 2 'speeds' of RAM modules is the sticker they place on the outside. The pc board is the same, the RAM chips are the same, the 'spd' information is the same. Generally, RAM modules from high quality manufacturers will exceed their 'exterior label' rating by a significant margin. The RAM is the same, in most cases, but it is labeled differently in order to SELL effectively. Most folks wouldn't buy PC3200 if their Dell is supposed to be using PC2700. After all, it would be the 'wrong' RAM - right?

BUT

the RAM you bought does indeed function reliably in your G5 - exactly as the retailer promised. Will it continue to function reliably? Probably. At least until Apple offers a firmware update that disables it. By then, I suppose, the retailer will no longer be selling that RAM as 'Mac compatible'.

PS, if the 3rd party RAM modules have the same OR higher operating limits (reflected in its 'spd' info) than the Apple-supplied RAM modules - you're probably not gonna be negatively affected by future firmware updates.

In the case of the thread's author, his 3rd party RAM has its 'spd' programmed to show operating characteristics which are inferior to the Apple-supplied RAM modules (ie, latency & frequency).

In peecee-land, it is accepted that 'spd' information will be incomplete, inaccurate, mis-spelled, or all the above. Hell, any and all information (esp. motherboard manuals) provided with PC hardware is laughable and of dubious origin. That's half the fun...translating badly translated technical information. PC hardware - where 'make walk' is the opposite of 'make run' - while 'make run' means 'power-on' (I love you, Abit).

[Mr. Bear]

Thank you for the detail explanation. I have opened a case with the local Apple Reseller and their supplier, shall see what sort of explanation they have.

From the various reading in the MacNN Forums, is that true to imply G5 requires the RAM it uses to contain the SPD information (also as per the G5 User Guide), but don't care what kind of information is in it? Weird indeed.

[Mr. Bear]

Well.. This only gets more interesting. Got another so called Apple G5 PC3200 DDR400 label 1GB module from another memory supplier here in Canada.

Guess what? Apple Hardware Test and System Profiler shows PC2700 again but the system ran just fine as in the first case. Does anyone who has 1GB module that is non-Apple supplied has these problem? Should I just go ahead and shell out the moo-lah to get Apple part?

Can anyone recommend any source for 1GB module that is "truely" PC3200?

Thanks in advance.

[pdovinh]

I bought four 1G modules advertized as "PC3200 DDR400" from MacSolutions.com for big bucks but Apple Hardware Test and System Profiler shows as PC2700.

See here:

HTTP://store.macsolutions.com/pgi-Pr...?DDR32002GBKIT

I emailed them and questioned this "false advertising" but have not received any answer. If I don't hear a proper response from them within the next 48 hours, I will bring the matter to the BBB and the FTC and a letter will be coming from my attorney.

pd.