I just tried a little experiment myself:

create table foo (

ID int identity,

X float)

set nocount on

declare @ctr int

select @ctr = 0

while @ctr < 1000

BEGIN

insert foo (X)

select rand()

select @ctr= @ctr + 1

END

select X from foo

order by newid()

compute sum(X)

select X from foo

order by newid()

compute sum(X)

drop table foo

The compute clauses in the identical select statements return different results. This is apparently caused by the ordering of the data.