Questions about GTX 970 and GTX 660Ti

"1. Is it possible to use the 660Ti as a dedicated GPU for PhysX on my motherboard (Asrock Pro4 Z77) next to the 970? If so, would a 750W (CombatPower) PSU be enough for both GPUs? Is it even enough for a GTX 970 alone?"

That's two questions in one.

- Yes you can dedicate your 660ti to Physx.
- I believe you are pushing it with with a 750w but remember your 660ti will only be doing a fraction of the work it use to . If you are looking at doing any over clock I would upgrade to a 900 Watt but only if your budget can afford it.

"2. If I use the GTX 660Ti as a dedicated GPU for PhysX, would it bottleneck the GTX 970?"

- Another GPU does not bottle neck each other unless they are SLIed, but the PhysX processing might be done quicker on your 970 than your 660ti which is what I am guessing you are getting at. I usually leave it up to the NVIDIA control panel to determine which device would be best for the PhysX but you could try some bench marks yourself to see which configuration is best. I recommend 3D Mark 11 because one of its tests is dedicated to Physics.

One thing to keep in mind about Synthetic Bench marks is that some times they will give one GPU a better score over another just because they don't run the same code for each...

http://www.tomshardware.com/news/nvidia-drivers-physics,5758.html

You can try this site to find a benchmark you like...

http://bulletphysics.org/wordpress/

"3. Which manufacturer brand is the best for the GTX 970 (EVGA, MSI, etc.)?"

That's subjective. The GPUs are all the same and will run the same. When it comes to over clocking some default BIOS will come with higher voltage and clock caps to give you more room for over clocking. So come with turboing built in to the bios. For the most part the biggest differences are the fan configurations and the looks. The speed differences are going to marginal unless you are looking at over clocking and need head room but even then you can re-flash the BIOS to what you need after buying the card. I do however like MSI's Afterburner software better than EVGA's X16 stuff but that a matter of preference.

"4. Would an i5-3570K CPU bottleneck the GPUs?"

In comparison to a Haswell processor yes a tiny bit. I would use this guide when comparing CPU bottle necks...

http://www.tomshardware.com/reviews/gaming-cpu-review-overclock,3106-5.html

1 combat PSU never heard of them so would not trust it for both cards, should run the 970 fine since it only calls for 500watts. The physX card can be used in your X4 speed X16 slot.
2 No
3 I choose between MSI, Asus and EVGA on price, many like the Gigabyte cards as well.
4 No.

There is no guarantee that a no name 750watt PSU delivers 750watts. Generic crap units have blown up on 50% load.

Everything after that was just "blah blah blah" for me, 900w for a 150w card and a 145w card! What?

I have a 750w Powersupply with 970`s in SLI..... works fine.

3570k is not going to bottleneck anything.

I was running SLi'd GTX560Ti's (Factory OC'd to 900mhz) on a HX620w PSU and that same PSU is now happily running OC'd SLi'd GTX660Ti's. So that's two 170w cards and now two 150w cards and no PSU issues whatsoever, so yes I think a 750w PSU is enough and as you won't be able to SLi your chosen cards there will be no CPU overhead to worry about so your i5 should be just fine and dandy.

It is not really the size of the PSU that is in question, it is the quality. Any Corsair, Seasonic, Antec, XFX, EVGA and so on 750watt PSU would run both cards but we know they deliver their rated output and they all have 4 x PCIe power connectors! This http://www.computeruniverse.net/en/products/90280151/inter-tech-cp-750w-combatpower.asp#data Who knows!

Not really and with these substandard PSU's there is always danger that they skipped on internal protection so if they fail on high loads they may take some if not all the other expensive bits with them.

I did say "a 750w PSU" not "that" or "your" 750w PSU.

That is basically what I am saying! I personally would not danger a $350 card on a substandard PSU and upgrade PSU to a quality unit.

Yes it can but use the money you get from selling your 660Ti to upgrade the PSU, having substandard unit is like having a ticking time-bomb since even electrical outages if the PSU does not have good internal protection can damage the other components.

^+1

It needs 2 times PCIe power that you have on your PSU and any quality replacement that you get. The card should simply work in your board but there are cases where people have had to upgrade BIOS to make them work but most of those have been with the H61 boards.

I was referring to that, if you have both cards in you will need 4 x 6pin!