Mark Twain wrote:
I took your good advice:

Here's the 8500:

http://i63.tinypic.com/rhn4tx.jpg

http://i63.tinypic.com/2nv5p3n.jpg

http://i67.tinypic.com/1zntqw4.jpg Verified matches for all power cables ?
Page 21 of 8500 "Owner's Manual"
and the 780: PWR1 (24 pin) PWR2 (4 pin) are standard items

http://i66.tinypic.com/2zea1oy.jpg

http://i65.tinypic.com/df7pmo.jpg 780 Rear case curvature ?

http://i65.tinypic.com/15qyydx.jpg Differences on cable exits, OK
780 has BTX layout
http://i63.tinypic.com/2znv0vl.jpg SATA4 cable to dual drive HDD bay at bottom
SATA2 cable to optical bay ?
Could be right-angle or left-angle connectors
Both seem to fit and have the right
screw patterns and the cables seem
long enough.

Robert

On the 780, you might want to look at your modular
cabling, and see whether the SATA peripherals need right-angle
or left-angle connectors.

I checked my (spare) Seasonic S12 and it appears to drape
the right way, for the angled connectors to fit the drives OK.
That doesn't mean necessarily that yours go the same way,
but since Seasonic makes their own supplies and doesn't
tend to buy contract supplies, there should be consistency from
one design to the next.

S12 cable + (for want of a name, I call this the
| SATA4 cable, with the four connectors)
|
+-X
|
+-X HDD \
| \__ use these two for bottom HDD bay
+-X HDD /
|
X --- straight connector is less convenient

You could check your SATA2 cable, to see whether there is
a straight one on the end. The straight end is OK, except
the wire will have to loop out into space, before the second
connector fits flush against the second optical bay (if you
have one).

It's too hard for me to plan a cable route for the 780 using
just my minds eye.

One thing missing from the 780, is a structural bar running
across the top part of the chassis. Sometimes, for "excess"
cable, like folding the main cable, you need a place to
tie-wrap the main cable to the bar, so it doesn't fall
down into the computer. I don't see a lot of tie points
to work with in the 780, to do a decent job of it.

But that's always a problem with computer cases, is not
enough "conveniences" for tying off things that need to
hang down.

That is part of planning, having a look to see how
everything will be kept in place. When there is a wad
of cables behind the PSU, something has to hold the
excess cables up.

On my newer machine, I made a custom adapter for a fan
to be mounted next to the (hot) Vcore regulator. And one
of the features of the custom adapter (a piece of board!),
is a sawn out area, where the folded excess cable from
the PSU, gets some support. It means I can't use all
the 5.25" bays, but the top bay has an optical drive,
while excess cable lays in the second 5.25" bay. So that's
how I solved that issue in the Antec Sonata casing.

This has always been a problem with my computer builds.
Some machines have the metal bar, it's riveted and cannot
be removed and always seems to get in the way. But it does
give a tie point, if there's no other way to hold up the
"cable wad". That structural bar gives the computer case
stiffness, but it gets in the way when you're trying
to maneuver the hard drive into its mount point. Modern
case designs have dispensed with it (a plus and minus
at the same time).

xps-8500_owner's manual_en-us.pdf
optiplex-780_service manual_en-us.pdf

Paul