Has anyone got replacement fans for a Asus Strix GTX660TI they want to sell or know anywhere I can get a pair?

I use "modded" (=I cut the square frame from the cooler, voiding warranty) Noctua nf-a9x14 PWM fans as a replacement on my ASUS Strix GTX 980 Ti. But you can use them without modding, if you remove the GPU's own fan frame.

Thanks Zoltan I will look into that.

I take it by "remove fan frame" you mean the whole plastic cover over heatsink?

I use "modded" (=I cut the square frame from the cooler, voiding warranty) Noctua nf-a9x14 PWM fans as a replacement on my ASUS Strix GTX 980 Ti. But you can use them without modding, if you remove the GPU's own fan frame.

Bought 2 fans that you suggested. Do I just fix them directly to the heatsink (how) and get rid of the shroud altogether. Will that be ok or is there a better way.

Sorry never taken a card apart before.

Well there is usually some form of 120° mounting points on the original fans. The hub support on the Noctua fans are 120° also. So see if you can cut away the square frame leaving only the hub support spars and shorten them as necessary to fit the existing mount points on the card. You will have do surgery on the power connector to utilize the power connection point on the card or simply plug them into a power connection from the motherboard or power supply. You will likely lose control of the fan speeds either way.

Well there is usually some form of 120° mounting points on the original fans. The hub support on the Noctua fans are 120° also.

No, it's 90° on both.

So see if you can cut away the square frame leaving only the hub support spars and shorten them as necessary to fit the existing mount points on the card.

I used some strong, but removable glue.

You will have do surgery on the power connector to utilize the power connection point on the card or simply plug them into a power connection from the motherboard or power supply.

I've cut the MB connector from the Noctua fans to make the cables the right size to reach the distributor connector inside the shroud, and stripped the 4 wires. Then I've put a little soldering to make the wires stiff enough to insert them directly into the connector (The black wire is the "ground" on both, the rest should be connected sequentially in both directions, regardless that the colors don't match).

You will likely lose control of the fan speeds either way.

No, this Noctua has PWM.

Bought 2 fans that you suggested. Do I just fix them directly to the heatsink (how) and get rid of the shroud altogether. Will that be ok or is there a better way.

Functionally it's ok (aesthetically... well it depends). I use cable ties (or wire twist ties) to quickly tie the fans to the fins. :)

Sorry never taken a card apart before.

Be patient while you do it. You'll need some very tiny screwdrivers (Phillips 0, 00)

Thanks very much for your help.