[jnrjr79]

Hi. I've been searching through some posts but can't seem to find a total answer here. I'm looking to buy 1 GB of RAM for my iMac G5 20''. Crucial is about $260, which seems pricey when compared to some other options, though I have liked Crucial in the past.

Here are the results I found on NewEgg, which I think are compatible:


NewEgg



I believe Corsair is supposed to be a reliable brand. Is there anything else here that would be good and under $200? The cheaper the better in my book, but I don't want to take any unnecessary risks while c hasing the lowest price possible.

EDIT: I see that link isn't working. I've got:
PDP Systems for $155
PQI for $156
All Components for $165
Gell for $177
Corsair for $185

[SouthPaW1227]

I will take delivery of my 20" iMac tomorrow, and I ordered a 1GIG DIMM to go w/ the 512MB I had Apple build it with.

I have ALWAYS used coastmemory.com for my Apple RAM (multiple PBs, G4 tower, and now a G5 iMac). They always have the lowest prices & FREE shipping and best service I know of. Their RAM always works great. I get the cheap RAM from them (not the HyperSpeed) and it's always been flawless for me. Also, at checkout if you select FREE shipping it'll knock $2 off 2-day shipping making it a $7.95 option, which is what I went for this time around and it arrived today.

Try them out, you'll save cash and be pleased w/ the quality.

[jnrjr79]

Originally posted by SouthPaW1227:
I will take delivery of my 20" iMac tomorrow, and I ordered a 1GIG DIMM to go w/ the 512MB I had Apple build it with.

I have ALWAYS used coastmemory.com for my Apple RAM (multiple PBs, G4 tower, and now a G5 iMac). They always have the lowest prices & FREE shipping and best service I know of. Their RAM always works great. I get the cheap RAM from them (not the HyperSpeed) and it's always been flawless for me. Also, at checkout if you select FREE shipping it'll knock $2 off 2-day shipping making it a $7.95 option, which is what I went for this time around and it arrived today.

Try them out, you'll save cash and be pleased w/ the quality.

Thanks for the recommendation. Looks like they could hook me up for $199.

[SouthPaW1227]

Comes up $179 + shipping for me. It's the 1GB DIMM Module PC3200 for iMac G5.

[jnrjr79]

Originally posted by SouthPaW1227:
Comes up $179 + shipping for me. It's the 1GB DIMM Module PC3200 for iMac G5.

I'm still getting $199. I click memory, then select Apple, then iMac G5 20'', and it comes up with a $199 option. Is there different memory for the 17''? Is that perhaps the issue?

[SouthPaW1227]

Nah, go to ramseeker.com, selection iMac G5 from the list, and then click 1800Memory (or CoastMemory, same ppl) from the 1GB list.

[jtaylr77]

DO NOT get the elixir memory from PC Supply. My iMac wouldn't even boot with 2x512MB sticks in it. I managed to get one 512 stick to boot it but after 5 minutes had artifacts and gave a kernal panic lock up. Not to mention...they charge a 20% restocking fee for memory that sucks. Ha! $35 it cost me to "try" it out.

[toneloco28]

I ordered the PDP memory from newegg to install in my iMac g5 and it worked flawlessy. Unfortunately the iMac had to go back due to a faulty mid-plane ,but irregardless the ram worked fine for the month I used it.

[cenutrio]

So, pretty much the Mac mini memory is the same that it is used on the eMac, right?

[PBG4 User]

Originally posted by toneloco28:
I ordered the PDP memory from newegg to install in my iMac g5 and it worked flawlessy. Unfortunately the iMac had to go back due to a faulty mid-plane ,but irregardless the ram worked fine for the month I used it.

I've used the PDP memory available from Newegg in my iMac G5 since September with no problems whatsoever. I would heartily recommend this RAM for the iMac G5.

[P]

Originally posted by cenutrio:
So, pretty much the Mac mini memory is the same that it is used on the eMac, right?

Current eMacs, yes.

[P]

Note that memory bandwidth is higher when using two identical memory sticks. The benefit may be minor in most cases, but if you're encoding video or something you will notice it.

[higuy83]

Originally posted by P:
Note that memory bandwidth is higher when using two identical memory sticks. The benefit may be minor in most cases, but if you're encoding video or something you will notice it.

Just wondering, but can you (or someone) explain why this is the case? I am picking up an iMac G5 tomorrow, and was going to have Apple upgrade the RAM to 512MB and then order an addition 1GB DIMM online.

This sounded great until the "video encoding" bit above... I plan on using iMovie frequently to encode video, and plan on using other relatively "hungry" applications. Would I be better off with a different RAM configuration then the one outlined above?

Thanks,

Brian

[P]

Originally posted by higuy83:
Just wondering, but can you (or someone) explain why this is the case? I am picking up an iMac G5 tomorrow, and was going to have Apple upgrade the RAM to 512MB and then order an addition 1GB DIMM online.

This sounded great until the "video encoding" bit above... I plan on using iMovie frequently to encode video, and plan on using other relatively "hungry" applications. Would I be better off with a different RAM configuration then the one outlined above?

Thanks,

Brian

I'll see if I can explain this... Essentially, when the CPU reads anything, there is a certain delay while the address is loaded onto capacitors on the chip itself. This delay is a rather large of the time it takes to read anything. To save pins on the memory package, the address is sent in two parts - a "column" and a "row". When reading more than one byte from a chip, you actually only send the column address once and then load the load the row addresses one after another, saving the time required to load the column address. The memory standards also include a few tricks for loading consecutive row addresses with a mimum of overhead, and you can read an entire column directly. 64 bit memory chips have 64 bits = 8 bytes in a column, so the maximum number of bytes you can read in this way, without sending the column address again, is 8. If you have only one chip, this is exactly how it works.

The G5 iMac has a 128 bit memory bus (memory chip to the memory controller). The memory bus works at 200 MHz DDR, meaning it can send 2 bits per pin and clockcycle. If each memory chip is only 64 its wide, it can only use half the bandwidth. If you use two chips, you can read from both chips at the same time, so it shouldn't matter if they're different sizes, right? Wrong. You see, if the chips are the same size, the memory controller acts as if it is really only one 128 bit chip. It sends the read instruction and the addresses once instead of twice, the same to both chips, and reads the data from both. If the chips are different sizes, it can't do this, because it would only work up to the size of the smallest chip. It has to send the instructions twice, one to each chip - assuming it really is 8 bytes in each chip. If it happens to be two consecutive 8 byte-words in the same chip, it can only use half the memory bandwidth.

In practice, it works like this: If the reads are 64 bits or less at a time, you earn nothing from a "twinned" setup. If the reads are between 64 bits and 128 bits, you earn half a memory cycle - waiting for the second half of the DDR-cycle instead of getting all of it at one time. If the reads are above 128 bits, you earn one cycle in latency (before the second half of the bus gets going). You also lose half the bandwidth when two consecutive reads end up in the same chip. It really is hard to calculate. I'd say that using two different chips vs. two identical chips is a rather small gain, provided each program only uses a memory size of (size of the smallest chip)*2. You lose a bit in latency vs. the identical chips, and in multiple reads of exactly 256 bits this mounts up to a lot, but in smaller or larger reads it's not a big deal. If the program in question uses more memory than (size of the smallest chip)*2 you start losing performance equal to the percentage of memory that is not "twinned". Just using once chip is much slower though, as the bandwidth is cut in half.