yes it is, recommended temps would be around 80 in room temp.
What you can do probably is get one of the pcie risers to separate them also try replacing the thermal paste with aftermarket stuff including doing some light cleaning on the ventiliation
TLDR
1. replace thermal paste/clean fans
2. pcie riser to separate them
A highly overclocked 780 Ti might come close to matching your cards, and without the heat or crossfire problems to boot.
Using crossfire 7970s too close together in a case with no ventilation would cook both cards (and prolly your mobo) in a very short time.
You could always get a bigger case and mobo but I suspect you've got space concerns.
i ran them this close together for nearly 2 months running Bitcoin mining at 100% with no issues.
Right now without gaming they are running idle at 37-41C. Once i fire up a game, u hear the fans spinning and it peaks at around 93-95C. Is that ok?
I don't think that would cook my cards/mobo right?
Quite reluctant to give up this Xfire combo as it's really very potent
You'll have to find a way to keep them further apart then. New case with proper ventilation planning, mobo etc.


A peak temp is the boundary they don't want you to hit over (or interpret it another way the off limit they want to stay as far as possible).that peak temp isnt ok? what is a peak temp to aim for?

During heavy stress test, my old system will reboot. Is it a heat issue or psu issue? Psu & gpu both running at full hold.
Will GPUs overheating cause a reboot or will it just throttle down?
just played Battlefield 4 for about 45mins, it went till about 87-88Deg Celsius. Is that ok?
Thats fine....
usually what kinda in-game GPU temps should one expect?
In that case i might have second thoughts about selling my 2x7970 and getting a single GTX780 / GTX780Ti (Not sure which would be a better match, i'm just doing single monitor 1920x1200)
You can try putting a piece of cardboard in between the two cards, i used it for my old 5870x2 crossfire, went from 80+ for bottom card , 90+ degrees for top card on load to 70+, 80+ respectively (during load).
Main issue is the two cards being too close together, causing the bottom card to block off any airflow and heating up the top card.