Please help a noob figure out what size PSU to order

3080guy

3080guy

3080guy

Associate
Joined
26 Sep 2020
Posts
221
Im not sure how to go about figuring out which PSU I need size-wise.

I have a 650 watt psu and want to be safe, so Id like to buy a 750watt psu, prior to ordering a 3080. I dont want to order something that wont fit my case.

How do I use windows or my eyeballs to figure out what size PSU I have.
Also, are there a few generic sizes, with size names, or is it not that simple.
I have no idea what to look for with regards to ordering the right sized psu.

(I also think my 650 watt psu will run my pc and a 3080, but Id like more overhead room and to use a 750watt psu).

Thanks for your help guys.
 
Of the two, is either a notably better brand?
Can I just go ahead and order one of those? (I didnt see case space/size referenced anywhere, so trust you can see dimensions.
Appreciate the help, cheers!
 
EsaT said:
Phanteks Amp is 140mm long.
https://www.overclockers.co.uk/phanteks-amp-750w-80-plus-gold-modular-power-supply-ca-09r-pt.html
Click to expand...
That looks perfect.

I think I could run a 3080 (according to an online calculator) on a 650 psu, but I read somewhere its better not to push your psu.
Someone here linked to a video where a chap ran a 2080 TI gaming rig from a 450w psu, so Im thinking 850 is futureproofing. Dont need 850 today.
Like the look of the super compact 750w Phanteks. Thanks EsaT.

Ive not opened a PC case to change anything in 15 years, hence the noob comment. Nothing looks anything like it used to. Can I do any damage by plugging anything in wrong, or not really? Is watching a few YouTube Videos more than sufficient training when swapping out a PSU?
 
OvEr_KiLL said:
make sure you disconnect it from the wall plug first then fit the new one and use the cables that come with it in the box '' dont '' try and use others! thern when its all connected reconnect the wall plug and turn it on
and 1 cable per power slot on a gfx card not 1 cable on 2 slots!!
Click to expand...
Thanks. The 1 cable per slot Ill remember. Cheers!
 
OvEr_KiLL said:
make sure you disconnect it from the wall plug first then fit the new one and use the cables that come with it in the box '' dont '' try and use others! thern when its all connected reconnect the wall plug and turn it on
and 1 cable per power slot on a gfx card not 1 cable on 2 slots!!
Click to expand...
Can you explain, would new PC's or just older PCs need to use cables from the PSU box? Why are you suggesting not to use existing cables?
Just keen to learn, thanks for your help.
 
Thanks guys.
And what of using one cable per power slot on the graphics card - does a 3080 need 3 cables to run from the PSU to the card (3 seperate cables)?
 
EsaT said:
While dedicated cable per connector is ideal, two cables with use of one extra daisy chained connector should be enough.
At least for not overvolted to even more crazier power consumption models.

Also 140mm long Seasonic Focus 850W would come with three cables, but stock situation has been bad for long.
Click to expand...
I went through the 850 psus one by one until I noticed those (140mm) and I noted the no stock situ! Well spotted, thank you. It looks like what Id like, in 140mm depth and 850w power.
 
Last edited:
I bit the bullet and ordered 1 750w PSU.
Will suit me for now, for the next few years and if I need to upgrade again post 3080, so be it.

Shame I couldnt get a 140mm 850w PSU but I really dont mind that much.
Huge thanks to everyone for all the help. Learned a tonne in the last few months.
 
Eliagon said:
Just in case (on the remote off chance this is interpreted wrongly) it might be worth making it clear that the pins at the PSU side change. The pins at the HDD / MOBO / GPU side are obviously standardised!
Click to expand...
Thanks Blue, Eliagon, and everyone else.
Used new cables, managed to post first time!
The 140mm suggestion was a good shout.
Like the strong smell of all the plastic whilst changing the cables over :D
 
When running PCIe cables from the PSU to, say, a 3080, is 2 cables enough.
Lets say the 3080 takes 3 cables (with 8 pins)

I installed the 750w psu
Ran 2 cables to it
The 2 cables both have 2 power connectors.

Can I use just 2 cables, if the 2080 I buy can take 3 cables?
I am not sure/cant remember how much power each cable, and the PCIe port deliver.

So I was thinking 1 cable plugs in to the 3080
The other cable plugs into the 3080 twice.
Just wondering if thats ok, if the card is the type which physically can take 3 cables.

Someone more intelligent than I could have worded that using a quarter as many words!
 
lord filbuster said:
Looking on Nvidia's site I think the 3080 takes 2 8 pin PCIe power cables, via some 12 pin adapter thing, so you should be fine, you'll just need to use both cables coming from the PSU, I wouldn't use the splitters really, putting the load over separate cables is usually better, even if technically one might be enough. They can get a bit warm if you run them at near capacity.
Click to expand...
I believe some cards take 2 cables. Some can take three seperate cables.
But I belive its also possible to figure out whether 2 cables meets the power requirement.

I swear my Phanteks amp 750 came with 3 PCIe cables. I counted them.
A week after I installed it, I cant find the third spare cable.
Remember folk saying only use cables that come with PSU.

I assume new graphics cards always come with the cables necessary to hook them up to any pcu and that there is uniformity there, in the edges of the PCIe connectors.
 
Should my phanteks 750w psu have come with 2 or 3 PCIe cables, would you guys guess, based on current trends?

I am sure I had 3 PCIe cables.
But only use 2 and now cant find the third after istallation.

Everything works. If I have 2 PCIe cables (both of which have 2x 8 pin connectors at the end) then I dont think I need to worry about getting a third separate cable (which I thought I had) for one day when I get a 3080.... i guess.
 
Last edited:
You must log in or register to reply here.
Back
Top Bottom