This discussion is archived
9591 Views 32 Replies Latest reply: Oct 18, 2007 11:06 AM by Applehead411
Currently Being ModeratedJun 21, 2007 2:39 PM (in response to tribe)Cool, Crucial is using Apple approved heat sinks like Ramjet is. Good to know. Thanks for the info!Mac Pro Octo-core (2 x 3GHz Quad-Core Intel Xeon), Mac OS X (10.4.9), -> Original Mac 128K (70 Macs total) Inc Mac TV, Mac XL (Lisa 2) and Color Classic II (Asia only)
Currently Being ModeratedJun 24, 2007 4:46 AM (in response to tribe)Wow. Is Crucial and Micron related in somehow? heheMac Pro Octo-core (2 x 3GHz Quad-Core Intel Xeon), Mac OS X (10.4.9), ->Original Mac 128K (70 Macs total) Inc Mac TV, Mac XL (Lisa 2), Color Classic 2
Currently Being ModeratedJun 24, 2007 6:01 AM (in response to The hatter)For the most part, there's no benefit to having all four channels populated, but in some rare cases the performance boost can be tremendous... we can assume that the scenarios where we do see a large performance gain are write bandwidth bound. Anandtech p. 12
When is 256-bit is not:
The major benefit that the Mac Pro seems to get from the use of FB-DIMMs is that its memory bus and FSBs can offer identical bandwidths at 21.3GB/s (ignoring the unknowns we discussed earlier about the efficiency of FBD). By using a lower pincount interface, Intel was able to fit four FBD channels on its 5000 series chipset and thus offer the bandwidth equivalent of a 256-bit wide DDR2 memory controller. p. 4 Anandtech
There is a small but significant performance advantage of about 10% by using dual-rank modules..
... Keep in mind that the performance of any specific program might or might not benefit from the optimal configuration. LLoyd blog
Mac Pro 2GHz 4GB 10K Raptor Cinema HD Mac OS X (10.4.10) WD RE RAID Aaxeon FW800 PCIe Sonnet Tempo APC RS1500 Vista
Currently Being ModeratedJun 26, 2007 11:58 AM (in response to The hatter)I've read all these posts but I'm still a little confused. We had the original two 512 sticks in and I added 4x1GB sticks.
For best performance should the 4x1GB be in A1/2 and B1/2 with the 512s in A3/4 or B3/4?
Or does it matter?macbook pro, Mac OS X (10.4.8)
Currently Being ModeratedJun 28, 2007 5:10 PM (in response to michael werth)From everything I read this is how I understand it:
- For max performance (Quad 256-bit) you need 4 identical FB-DIMMS in the 1st two slots (source is ramjet.com - memory reseller).
- Put the largest FB-DIMMs in the A1/2 and B1/2. The Mac won't have to swap to the secondary (B) memory slots (A 3/4 & B 3/4) as much which will give a bit of latency.
So by adding 4 x 1GB FB-DIMMS into A 1/2 and B 1/2, and putting your 2-512M FB-DIMMS in A 3/4 would be the best choice.Mac Pro 8-core (2 x 3GHz Quad-Core Intel Xeon), Mac OS X (10.4.9), ->Original Mac 128K (70 Macs total) Inc Mac TV, Mac XL (Lisa 2), Color Classic 2
Currently Being ModeratedJun 28, 2007 5:12 PM (in response to Mac512-Guy)This is the info from http://ramjet.com/macpro.asp This is the only source I found for this information. I put it in here to add to the conversation and clarify what I stated.
Overview: The Mac Pro uses a memory type called an FB-DIMM (Fully Buffered - Dual Inline Memory Module). Ramjet FB-DIMMs work in all Mac Pro models including the 8-core. There are eight (8) slots, and the FB-DIMMs must be installed in pairs (2x identical) or quads (4x identical). Matched Quads run 5-10% faster, because the memory controller is able to address all four FB-DIMMs as a single 256bit memory bank. The original 1Gig is installed as a pair of two 512mb FB-DIMMs. The system maximum is 32Gigs with the installation of eight (8) 4Gig FB-DIMMs (two 16Gig quads).Mac Pro 8-core (2 x 3GHz Quad-Core Intel Xeon), Mac OS X (10.4.9), ->Original Mac 128K (70 Macs total) Inc Mac TV, Mac XL (Lisa 2), Color Classic 2
Currently Being ModeratedJun 29, 2007 6:46 AM (in response to Mac512-Guy)Some more background on FBDIMMs:
http://www.anandtech.com/mac/showdoc.aspx?i=2811&p=4Mac Pro 2GHz 4GB 10K Raptor Cinema HD, Mac OS X (10.4.10), WD RE RAID Aaxeon FW800 PCIe Sonnet Tempo APC RS1500 Vista
Currently Being ModeratedJul 23, 2007 7:50 PM (in response to Kappy)Could you help me out, I just recently bought 4 gb of memory, 1 of: Kingston ValueRAM - Memory - 2 GB - FB-DIMM - DDR II - 667 MHz - CL5 - 1.8 V - fully buffered - ECC (2 Dimms) but when I installed them on the mac pro it only recognized 1 dimm and only 2 gb of memory, I took of the 2 of 512 that comes on the mac pro, thinking that might be the problem but it didn't work insted when I put them on the B1/B2 slots it recognized the the 2 512. What can I do?
mac pro Mac OS X (10.4.10)
Currently Being ModeratedJul 24, 2007 11:09 PM (in response to reyescfd)Besides the first pair of 1 Gb the other memorys must be of the same maker.
Don´t ask me why but when they put the memory on my machine at the beggining it was only recongnizing 3GB and it has 5, so I take it to the store and we notice that they had put me one pair of the same brand and the one causing the trouble was the other pair with two different ram brands, the he changed that pair for one identical pair but different brand than the other and still didn´t recongnzed them, then he put me and identical pair than the first ones and it work.
So my guess is that besides the 1GB that comes with the machine the other ram cards should be from the same brand.
Well I am no sure but that´s what happened...Mac Pro, Mac OS X (10.4.10)
Currently Being ModeratedJul 25, 2007 5:49 AM (in response to Kappy)When I buy my Mac Pro I was planning on ordering with the stock 2x512 memory. Then I was planning on upgrading to 4 gigs and was originally considering 2x2 but it sounds like 4x1 would be ideal because of the system utilizing the channels adequately. Ideally down the line I'd buy an additional 2x2 so the point would be moot, but now I'm not sure which way to go.PowerMac G4 Digital Audio with Sonnet 1.2ghz and 1gb RAM ; MBP (2 Ghz Core Duo)
Currently Being ModeratedSep 29, 2007 10:12 AM (in response to MacWord)Wow this is getting confusing. I have another machine-specific question:
I just received my base model Quad Mac Pro with two 512 DIMMs from Apple for a total of 1GB.
I can only afford a 2GB kit (1GBx2 sticks) for an upgrade right now, and I'm look at kits from Crucial and OWC. Should I instead by 4 512 sticks, or go with this 2GB kit and put those two sticks in the A slots? If so, should I move the 512 sticks to B slots or get rid of them entirely?
Any advice on how best to set this machine up with my current configuration and what I can afford is much appreciated.15" MacBook Pro, 2.66 Quad Mac Pro, Mac OS X (10.4)