Maximum Possible upgrades for PowerMac G4 MDD

Overclocking beyond 1.5 GHz will likely result in a dead processor or two within a short amount of time.

How much time decreases exponentially as the CPU's are clocked up....

Don't kill it unless you're ready with a replacement for "reasonable" overclocking.....

Watercooling is cool. Aqua-Mac has some beautiful mod's:

Homepage aqua-mac | aqua-mac.com

Internal RAID is lots of heat.

MDD's run hotter than hades at stock speeds with 1 hard drive.

Might be better to get a PM supporting eSATA controller and use an external RAID.

Otherwise, remember to keep an ATA boot drive in case boot isn't supported by the RAID controller (likely not).

Firmtek Seritek controllers are the surest way to get full OS X support.

japamac wrote:

Overclocking beyond 1.5 GHz will likely result in a dead processor or two within a short amount of time.

How much time decreases exponentially as the CPU's are clocked up....

Don't kill it unless you're ready with a replacement for "reasonable" overclocking.....

Like I did? hahahah yeah I found 1.5 to be stable as described here: http://bitsandpieces.info/Multipliers.htm

However I completely burned a DP 1.42GHz board by OC it to 2.3GHz it fried after a week (and constant KPs) wasnt very stable fr longer than an hour or two but for that hour it was fast as mess and ran like a champ. So I bought a DP 1.33GHz board to replace it. Just left it as is.

I found 1.5 to be stable as described here:

Faster has been tried by many over the years.

In the end, the experience of all those prior has shown that even the best chips are reaching the limits of stability over 1.5.

I remember reading about guys with brand new dual 1.42 machines burning them up going fast.

LOL, did they cry the blues...... especially when Apple Care didn't cover them.....

Apple did a good job of chip selection and in choosing the OEM clocks of those 7450/55 chips, and didn't under-clock/perform them as they were accused of with previous models.

Funny, but it seems almost no G4 processor overclocks (long-term succesfully) much more than two steps above OEM, with the majority only going one step over before instability.

OK, some 733 MHz QS processors overclock to 933 MHz (4 steps?), but those things don't have a L3 cache and aren't worth the effort.

Those were a ripoff from the git-go.......

Yeah seems to me that they are what they are. past 1.5GHz they just burn up. I know that from personal experience.

I totally agree that 1.5GHz is the upper limit for the OEM 1.25, but it's only the 7455Bs that I'd try to push that far. If yours is a 7455A, I'd just leave it alone. Additionally, I don't think upping core voltage is a line worth crossing. If it's not stable at 1.5GHz with stock voltage, I'd drop it down to 1.42GHz. Upping CV adds even more heat.

If it's stable at 1.5GHz and you're running CHUD nap mode, it'll probably be okay. There are, of course, no guarantees. 1.5GHz will give you a full 20% increase in CPU power, which is enough to notice, enough to make it feel like a faster machine.

I've played with this all kinds of ways and my rule of thumb is to downclock a notch if the CPU can't handle a heavy load and remain under 50C. That may be an overly cautious approach, but I've never lost a CPU.

Again, if it's a 7455A, I'd leave it alone.

I had an internal RAID in one of mine for a while. I should mention that all of my MDDs have an additional 80mm fan positioned between the heatsink and the back of the case (listen to Japamac about the heat).

I ended up replacing the RAID with a single WD Black drive and, even though the RAID had more impressive benchmarks, I can't say that I notice any difference in actual use. It feels just as snappy with the single Black drive and you'd need a stopwatch to detect any difference in boot times or how quickly apps open.

No regrets about making that change.

I think you would be better off & possibly cheaper to get a G5 2.7GHz DP Mac.

http://www.everymac.com/systems/apple/powermac_g5/stats/powermac_g5_2.7_dp.html

Even thoughh you might increase the processor speed, your G4 MDD has a Bus speed of 167MHz, a RAM speed of 333MHz, a 2GB RAM max.

The G5 2.7GHz DP Mac has a Bus speed of 1.35GHz, a RAM speed of 400MHz, and up to 8GB RAM. Overall it will be much faster than the upgraded G4.

 Cheers, Tom 😉

It's not just the temperature.

The chip has to be able to reliably function without panic or freeze at a given clock rate.

That "guy" happens to be an accomplished modder, G4, G5, Hackintosh, etc., and like many others in the know, has stopped the overclocking at a stable, reliable speed.

Don't take our collective word for it.

Go as far/fast as you can/want.

MDD mods are nothing new. There isn't an overclock that you can try that others haven't.

It just happens that the 1.25/1.42 7455 chips don't work well beyond 1.5.........

If they did, there would have been commercially available units from the likes of GigaDesigns, PowerLogix, etc.

Those companies gave us many performance choices in the day.

But they didn't offer anything beyond 1.5 GHz.

Maybe they, too, knew what they were doing.......

No idea in that produvt, but I'd trust these to be bootable & work properly on Macs...

http://eshop.macsales.com/shop/SSD/OWC/Mercury_Extreme_Pro/Legacy_Edition

Silicon Images chipset cards do not support boot to connected drives.

ONLY Firmtek controller chips support boot to connected drives........

But, you can use 2, 3, 4 SSD, SATA 2 or SATA 3, multiple ATA, whatever, with the proper controller.

For bootability and the best drivers, Firmtek.

Otherwise, for relatively reliable drivers in RAID without boot ability, likely the best choice is Highpoint.

For hit and miss support at a budget price (get what you pay for) Silicon Images.

Those OWC PATA adapted SSD's are kind of a waste.

Sure you'll get max throughput, but limited to ATA 66 or ATA 100 speed.

Haven't seen anyone try and RAID them, either.

Add a PCI controller and get at least SATA 1 throughput.

Any Sandforce controller based SSD will be bootable when connected to a Firmtek Seritek SATA controller card.

There is also one 2 port Sonnet controller card that uses the Firmtek chip and does, therefore, support boot to connected drives.

Thanks jmac, cant afford to test such things any more. 🙂

Yes, yes, and yes.

Also, the level 2 cache can only take so much. Even if you end up with a higher clocked CPU, in terms of performance, you've gone in the wrong direction if you lose your level 2 cache.