new video card decisions

O/S win7
cards under consideration
W8100
R9 295
Titan

Projects
F@H
MW@Home
Collatz

Pros and cons please from others much more adept... Even suggestions. :-) DP performance a must.

The AMD FirePro W8100 has a Hawai Pro GPU, 2560 shaders, 160 TMAP Units and 64 ROPs. It is the 2nd best Workstation FirePro after the Hawai GT equiped W9100 (there are also Server FirePros, beginning their model name with a 'S', as the S9150, S9170 and the S10000).
The W8100 has a SP performance of 4218.9 GFLOP and a DP performance of 2109.45 GFLOP (professional card, gets it DP at 1/2 of the SP).

The R9 295X2 (there is no single GPU R9 295) has two Hawai GT GPUs, 2x 2816 shaders, 2x 176 TMAP Units and 2x 64 ROPs.
The R9 295X2 has a SP performance of 2x 5733.326 GFLOP and a DP performance of 2x 716.672 GFLOP (consumer card, gets it DP at 1/8th of the SP).

Titan, a minefield. Note that the last Titan, the GeForce GTX Titan X, only has 192 GFLOP DP! The older Titan Z and Titan Black both have a significantly higher DP value, but you can get the performance even higher by altering a setting in the BIOS of the cards:

"Double precision performance of the GTX Titan & GTX Titan Black is either 1/3 or 1/24 of single-precision performance depending on a user-selected configuration option in the driver that boosts single-precision performance if double-precision is set to 1/24 of single-precision performance,[9] while other Kepler chips' double precision performance is fixed at 1/24 of single-precision performance.[10] GeForce 700 series Maxwell chips' double precision performance is 1/32 of single-precision performance.[11]" -from wikipedia

Setting the DP at max, the dual GPU GeForce GTX Titan Z can reach 2707 GFLOP (for 8122 GFLOP SP).

Assuming prices in the USA are comparable with those in Europe -which is untrue, better check Newegg or so-:

• Titan Z will set you back between 1500 -Gigabyte- and 2500 -Palit- bucks
• W8100 costs 1125 and
• R9 295X2 can be bought between 710 and 1300 bucks

Thankyou. :-)