New GPU - Loop - Heat

[noobftw]

I currently have an i9 7900x and a 1080TI FE, both are overclocked, CPU is at 4.6Ghz.



All of this is running in a single custom waterloop with x2 Alphacool NexXxoS ST30 Full Copper 420mm radiators (Push configuration) and a D5 Pump. The case is a Dark Base Pro 900, one of the radiators is intake (front), and one is exhaust (top), only other fan in the system is an exhaust fan (140mm) out the back of the case.

Current System Temps while gaming:

Water Temp: 40c

Water Pump Speed: 2.9

Radiator Fans RPM: 1000/1100 RPM

CPU Temp: 62-72c

GPU Temp: 46c

Question, if I replace the 1080TI, which has a TDP of 250 stock (FYI my GPU is overclocked so will be higher), with the 3080 (TDP 320) or the 3090 (TDP 350), and don’t overclock the new GPU, (1.) will my radiators be able to handle the extra heat?

(2.) Will I have to increase my fan speed? By how much…

(3.) Will the water loop run hotter, how much hotter? Will it be too hot for the soft tubing I use?

(4.) Will the additional heat of the 3080/3090 heat up my CPU more than it is now?


Thanks in advance.

 

[noobftw]

1) yes, 840mm of radiator is lots
2) impossible to say, but I would not expect any major change
3) possibly, can't predict how much. Not too hot for soft tubing IMO
4) again possibly.

You're looking for science when watercooling is often more like an art. Because I don't have your exact setup, I can not model answers to your questions that will give you hard numbers.

e.g.

The D5 is at 2.9. But what's the flow rate?
The fans are at 100/1100 rpm but what fans are they? How much airflow are they achieving?
What's the room ambient temperature? Do you have the window or door open or is it a closed room?

I don't know all those answers and I doubt you do so neither of us have hard data for every part of your loop.

Two 420mm ST30 rads is a lot of cooling but even Alphacool don't specify what the cooling capacity is. Because it depends on the fans, the ambient temp, the air resistance through the rad. i.e. a radiator outside a case with a given fan can be measured. Put the radiator in a case and the fans are now pushing air into or out of a case. Is it closed, restrictive, wide open? Are there exhaust fans? has the case been setup for positive or negative case pressure? To what extent?

I'm really not trying to be a Richard but every watercooling system is unique. You should be well within limits with two 420mm rads. If it becomes too hot for you, add fans to make it push/pull or put stronger fans in.

The fans are Be Quiet Silent Wings 3, max RPM is 1500
Room ambient this time of the year varies between 25 -30c, both windows wide open-door shut, but it's a small room, gets hot quick.
The fans are in push configuration on the radiators, front radiator takes air into the case, then top radiator exhausts it, back 140mm case fan also exhausts air. The case dissipates air quite well, as I have modded it, the top radiator (exhaust) is unrestricted, while the front is for the most part unrestricted.