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EDO vs FPM Memory
- Thread starter cobalt60
- Start date
Byrd
Well-known member
Short story is I don't think it matters in most Macs. I believe EDO DIMMs will work in all FPM 5V model PPC Macs at FPM speeds, but there are some caveats for certain models here:
Power Mac DIMMs
Secure online sales of high-quality Macintosh memory products, hard drives, systems, RAID, monitors and other peripherals
www.macgurus.com
Well, I think I found the answer at the following link:
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4400 takes 3.3V and supports EDO
5500, 6500, and PM 6400 take 5V and support EDO
7300 thru 9600 take 5V and will accept EDO modules, but they will operate in FPM mode
7200 should not have EDO modules installed as this could damage the mainboard
"
So, that answers my original question. I'll ask a new one; is there anything to look out for memory specs for higher performance? Could 50ns offer any benefits? I think the 7300-9600 can support either 2K or 4K refresh rate. Is 4K faster? Is there memory that is faster than 4K, say 8K, that will function in these Macs, just running at 4K?
Mac Memory Explained - OEMPCWorld
All you ever wanted to know about buying memory for you Macintosh Confused about the different types of memory that are being used in current Apple products? What is meant by FPM, EDO, SDRAM, and SGRAM? Which Power Macintosh computers support these different memory types? Fast-Page Mode (FPM)...
www.oempcworld.com
"
4400 takes 3.3V and supports EDO
5500, 6500, and PM 6400 take 5V and support EDO
7300 thru 9600 take 5V and will accept EDO modules, but they will operate in FPM mode
7200 should not have EDO modules installed as this could damage the mainboard
"
So, that answers my original question. I'll ask a new one; is there anything to look out for memory specs for higher performance? Could 50ns offer any benefits? I think the 7300-9600 can support either 2K or 4K refresh rate. Is 4K faster? Is there memory that is faster than 4K, say 8K, that will function in these Macs, just running at 4K?
My motivation is, I want to experiment with overclocking the bus speed in 7500-9600 computers. When I was younger, I always wanted a Power Computing unit with 60MHz bus. When I got a beige G3, I ran the bus at 83.33MHz, and it worked perfectly. When I got a Gigabit Ethernet G4, I ran the bus at 120MHz, and it also worked perfectly.
I just read an article on how Power Computing got their bus to run at 60MHz, and in that article, they said that some 7500-9600 actually will run at 60MHz. Now as history has shown us, that isn't true for the majority of 7500-9600 out there. But, I intend to try. I just bought 7300, 7600, 8600, and 9500 mainboards, so I can cherry pick and maybe see what differences there are between these models. I theorize that the 7300 may do well due to lacking the AV circuitry, one less thing to worry about, but that theory could be way off, as could my hopes to get anywhere near 60MHz. I will consider 53.33MHz to be a massive success. This subject should probably have its own thread.
Long story short, I want the highest spec RAM I can get. I am not looking for higher memory performance necessarily, I am looking for extra stability. EDO is considered to be higher spec than FPM, and I have heard it works with zero issues in these Macs, so I think it would be more desirable for me, but please let me know if that is incorrect.
I just read an article on how Power Computing got their bus to run at 60MHz, and in that article, they said that some 7500-9600 actually will run at 60MHz. Now as history has shown us, that isn't true for the majority of 7500-9600 out there. But, I intend to try. I just bought 7300, 7600, 8600, and 9500 mainboards, so I can cherry pick and maybe see what differences there are between these models. I theorize that the 7300 may do well due to lacking the AV circuitry, one less thing to worry about, but that theory could be way off, as could my hopes to get anywhere near 60MHz. I will consider 53.33MHz to be a massive success. This subject should probably have its own thread.
Long story short, I want the highest spec RAM I can get. I am not looking for higher memory performance necessarily, I am looking for extra stability. EDO is considered to be higher spec than FPM, and I have heard it works with zero issues in these Macs, so I think it would be more desirable for me, but please let me know if that is incorrect.
Coloruser
Well-known member
I remember those days in the late 90s when i had dozens of TNT and Tsunami mainboards mounted on racks to test our G3/G4 cards that sported dials to adjust the bus speeds. I did experiments with them with edo and fpm and seem to remember that it was not the type but the speed that made the difference. 50mhz was quite slow even by standards of those days. First thought was that Tsunamis might be better suited to at least reach 60mhz as they lack internal video but it turned out that the 7300 and 7500 TNTs were the most forgiving ones. On the other hand, the Umax storm surge 9500 derivative was also more flexible on bus speed than the 9500 itself. Checking my notes from the lab days indicates that 80% of the TNTs ran stable at 60mhz while less than 50% of the Tsunamis did that - but your milage may differ as the empirical base was just a few dozens units running in parallel as testbeds.
Amazing info. Do you remember what speed 60-80% of the Tsunamis would run at? 56MHz? Yes I like weird numbers.
Were you able to try 50ns memory? Pretty sure those exist.
I'll probably try things like looking for hot motherboard chips, and putting heatsinks on them and maybe the VRMs.
Coloruser
Well-known member
Can you link to that article?
As far as i remember, only the Catalyst (7200) based units - namely the PowerCenter, PowerCenter Pro, PowerCurve, PowerTower - really can run at up to 60 Mhz if the CPU runs at an even multiple of 60. However, they never worked reliably with the G3 and G4 cards that we developed in the late 90s - not even with high bus delays. There was something special in the implementation. The Catalyst was not designed to have a CPU slot and thus they did some real magic. Just like with their Nubus/PCI bridge machines. Their Tsunami derived ones (PowerWave 3 PCI and PowerTower Pro 6 PCI) units „suffer“ the same limitations as Apple‘s own Tsunami/TNT or Umax S900 etc. but worked flawlessly with mist G3 and G4 aftermarket cards.
As far as i remember, only the Catalyst (7200) based units - namely the PowerCenter, PowerCenter Pro, PowerCurve, PowerTower - really can run at up to 60 Mhz if the CPU runs at an even multiple of 60. However, they never worked reliably with the G3 and G4 cards that we developed in the late 90s - not even with high bus delays. There was something special in the implementation. The Catalyst was not designed to have a CPU slot and thus they did some real magic. Just like with their Nubus/PCI bridge machines. Their Tsunami derived ones (PowerWave 3 PCI and PowerTower Pro 6 PCI) units „suffer“ the same limitations as Apple‘s own Tsunami/TNT or Umax S900 etc. but worked flawlessly with mist G3 and G4 aftermarket cards.
Coloruser
Well-known member
For 60 - 66 Mhz bus speed, you needed 60 ns RAM as 70ns RAM might be too slow. I have never tried any 50ns Ram and I guess it may has not been widely used as the industry moved fast to SD RAM with 66 Mhz and above.
To answer your question, the majority of tsunami testbeds were based on Umax S900s and the soldered L2 cache was as far as I remember one of the limitations to go past 55-56 Mhz. But Apple‘s tsunamis did not do it much better - but they were a bit more flexible when the cache Dimm was unpopulated. The L2 was used as L3 if present with a G3 or G4 card installed. And, using L3 did not make the systems any faster.
To answer your question, the majority of tsunami testbeds were based on Umax S900s and the soldered L2 cache was as far as I remember one of the limitations to go past 55-56 Mhz. But Apple‘s tsunamis did not do it much better - but they were a bit more flexible when the cache Dimm was unpopulated. The L2 was used as L3 if present with a G3 or G4 card installed. And, using L3 did not make the systems any faster.
Here's the link:
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Note: Power Computing has modified and enhanced PowerTower and PowerCenter 166/180 MLBs (the so-called Catalyst Plus) to run at a maximum of 60MHz. Enhancements include ASICs and L2 cache certified reliable beyond 55.33MHz.
"
I do believe I saw a nearly identical statement in a different article, but I could be confused.
Power Computing RAM Specifications
Secure online sales of high-quality Macintosh memory products, hard drives, systems, RAID, monitors and other peripherals
www.macgurus.com
"
Note: Power Computing has modified and enhanced PowerTower and PowerCenter 166/180 MLBs (the so-called Catalyst Plus) to run at a maximum of 60MHz. Enhancements include ASICs and L2 cache certified reliable beyond 55.33MHz.
"
I do believe I saw a nearly identical statement in a different article, but I could be confused.
