Hi,

I have been running 2 GTX750Ti cards for GPU grid on my system with a 600W PSU for a while now and decided to upgrade one of the cards to a GTX970. Both seem to be running happily with the current PSU.

Although this is the case I was wondering whether or not this will be safe in the long run as the GTX970 has a considerably higher power draw that the 750's.

The PSU is a Corsair CX600.

Stephen

Hi,

Thanks for the advice. I'm due a new psu and plan to replace the second 750 soon so will look at the RM.

Much appreciated.

Stephen.

Hi,

Thanks for the advice. I'm due a new psu and plan to replace the second 750 soon so will look at the RM.

Much appreciated.

Stephen.

skgiven is spot on with his math. You should always work out how much you are drawing from each rail with multi GPU systems.

One quick sanity check is whether you have enough plugs on your power supply for your equipment. Your CX600 has two which is the right number to run your GTX970. Most 750TI's don't need any. There are a few overclocked models that do but most do not. So, the sanity check passes and the math works out. Your system should be fine with the CX600 as it is.

FWIW, my dual 750ti system draws 144 watts from the wall with an ungraded 80+ rated 380 watt supply. That makes it around 115 watts for the mostly idle CPU and two 750Ti's crunching GPUGRID assuming an 80% efficient supply.

I budgeted 200 watts each for factory overclocked GTX970's to be safe in my build. The Nvidia control panel says my GTX970 is currently drawing 154 watts with a cap of 201 on a GERARD_CXCL12 work unit. I only have one card so far but built the system to take two. A pair will use up to 400 watts. Add another 200 for the rest of your system and you are looking for a power supply of at least 750 watts with 4 PCIe power plugs to run at 80% load. The supply proposed by skgiven is a decent choice. I might look at a slightly bigger supply to give a bit more headroom for your higher power CPU as I prefer to aim for 60% load on more modest systems. It is tough to get a power supply with enough PCIe plugs to run a pair of GTX970's rated less than 750 watts but they do make them so the sanity check alone is not enough.

I rarely recommend the higher 80+ ratings below 600 watts. They will never pay for the extra purchase price in saved electricity. You are at the point that you should consider a higher rating (gold / platinum ) if you can get one at a good price. You might make back 20 dollars. You probably won't make back 50.

Hey, thanks for the reply. I went for the corsair 850i platinum series to give myself room for future upgrades. I found that the 970 is a vast improvement on the 750Ti and decided to just go ahead and get another. Just waiting for delivery of that atm. Unfortunately I couldn't stretch to the 980 just yet.