There is X5680 which is basically the same as W3680 but has dual QPI and thus supports dual CPU configurations.
Well there is the $999 (W3680) versus the $1663 difference factor too.
🙂
There is a $223 difference in price between the W5680 and W5670. Multiply that by 2 : $446 . Add a 40% Apple profit margin: $624 . So, you'd have a top end Mac Pro that was $700 (gotten have price end in "99" ) more expensive. The more expensive the product, the less folks are going to buy There is a limit to what folks will pay. Additionally, the higher the core box the less likely going to buy the add-ons (memory, drives , etc. ). $700 would just about give a CTO 12 2.93 box 16GB of memory which is a reasonable config for that number and speed of cores. Apple still gets the extra $700 and many customers are happier because it is a better set up out of the box with just one purchase order.
Heat dissipation probably plays a factor too.
Did those previous model 300W dual processor packages boxes have a spotless long term record on power supply problems ?
Folks can say the power supply is the same as before (with 130W processors ), but two factors:
1. Internal case model to adjust for the effectiveness of the multiple thermal zones. Graphics cards are getting more power greedy than 3-4 years ago.
2. The power supply is a zero sum game. The same folks throwing mega dollars at the base box the receive from Apple are likely much more inclined to fill every open slot with stuff. So probably not a tendency to add more of just one subcomponent it will be more on every single dimension possible.
If have 3.33GHz probably going to stuff as much memory as possible in so that can leverage more of that full speed, more disks to leverage more of the speed, more GPU horsepower to display the results. The standard GB Ethernet has gotten be tooo slow for that kind of speed so some higher I/O card. The disk I/O is too limit so RAID card. Oh look, an empty SATA connector in the optical drive.... yeah stick something on that too and run it constantly. Not every user on the highest end box is that way, but that is one of the places in the product spectrum they tend to congregate.
Wouldn't be a very surprising result if Apple went back through previous generation Mac Pro warrantee power supply replacements trouble tickets and found a slight positive correlation between people who run the supply at higher fractions of constant power and those who needed replacements during warrantee period. Apple can't really control folks from adding new components into every nook an cranny. However, they can improve profitibility but given those folks a broader power envelope to work with by capping the dual package offering at 190. That won't remove all of the power supply failure claims but definitely helps remove the more unnecessary ones.
So yeah there is some slack in the 900-980W standard supply in the configurations as shipped by Apple, but using every single last drop of power isn't a prudent idea. It is even worse idea to ship the box from the factory with a small reserve.