[8.38L] RX 570 into an Optiplex 990 SFF

Valantar

Shrink Way Wielder
Original poster
Jan 20, 2018
1,890
1,822
I managed to mod my Optiplex 790 SFF to take a standard Fortron TFX 300W psu with the original MBO, dremeled out the top cover holders at psu side, and the big hump under the original psu on the inner component metal tray, leaving all the original mbo mount points. Also i had to dremel a bit from the back to get the power plug to be accessible and thats all whats visible modificaion wise from the outer side of the case. Sadly dont have pics at this time, but seems much easier than the custom psu adaptation you had to do.
Which way is the fan on your unit pointed? Towards the motherboard? I did consider doing a similar mod, but the only TFX unit available to me where I live would be a BeQuiet 300W version that doesn't even have PCIe power except through a molex-to-PCIe adapter, which isn't good enough for me. It also for some silly reason has two 12V rails, meaning each is limited to 13A (156W) which is barely enough for the RX 570. It would have been cheaper and possibly easier to do, but it would also have been a far inferior solution both in terms of noise, efficiency and upgradeability. Also, DIY is so much more satisfying :D
 

Frung

Chassis Packer
Mar 1, 2018
16
7
Yes, the fan is pointed towards the motherboard. My psu also doesnt have the gpu pcie connectors(GT 1030 atm), and TFX being a standard having different options in many price ranges 20 - 60 €. That said, molex-to-PCIe adapter from the 2x molex i have on this PSU sound like a legitimate option to me for powering the likes of gtx 1060 on the Optiplex. As i understood, the original psu of sff 790 and 990 isnt very highly regarded, latter even more so quality wise anyways, and the 60w bump up to a bronze 300W, is more than the TDP difference of gtx 1050 TI to gtx 1060, 75 to 120w. Set the power limit in Afterburner to 70% and voila, shoudnt be a problem ;) This is all theoretical, dont have the 1060 atm. Even better option would be gtx 1650 super with 100w tdp, though much less price economic.
 

owliwar

Master of Cramming
Lazer3D
Apr 7, 2017
586
1,081
wow!! I like this very much :)

I'll read it all later, but this is looking really nice
i'm inspired
 
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Valantar

Shrink Way Wielder
Original poster
Jan 20, 2018
1,890
1,822
Yes, the fan is pointed towards the motherboard. My psu also doesnt have the gpu pcie connectors(GT 1030 atm), and TFX being a standard having different options in many price ranges 20 - 60 €. That said, molex-to-PCIe adapter from the 2x molex i have on this PSU sound like a legitimate option to me for powering the likes of gtx 1060 on the Optiplex. As i understood, the original psu of sff 790 and 990 isnt very highly regarded, latter even more so quality wise anyways, and the 60w bump up to a bronze 300W, is more than the TDP difference of gtx 1050 TI to gtx 1060, 75 to 120w. Set the power limit in Afterburner to 70% and voila, shoudnt be a problem ;) This is all theoretical, dont have the 1060 atm. Even better option would be gtx 1650 super with 100w tdp, though much less price economic.
I'm not saying a molex adapter wouldn't work or isn't a legitimate option, I'm just saying I don't like it - I could accept a janky branching power solution when it was DIY, but not if I'm actually paying for something better than stock. Having two Molex chains running around inside a tiny case like that is anything but ideal, especially when they'll be running close to spec powering a 150W GPU.

As for output, given that I've been running my RX 570 at -20% power off a 240W PSU with a 17A/204W 12V rail, I'm perfectly aware that a 300W unit is perfectly fine for this kind of power draw. If you had read my posts about modding the PSU and running the GPU at -20% power limit you'd also know I'm very well aware of just how shitty it is - the 65% rated mean efficiency really does say it all. Not that it matters much here, but remember that the PCIe slot in the Optiplex maxes out at 35W, so it can't power a GTX 1050 (Ti) without external power, at least on paper. It might not actually be current limited, but it might, or the traces might just burn out from the excessive power - not a good idea trying either way. Given my experiences with a 150W RX 570 I would expect the stock PSU to handle a 120W 1060 perfectly fine at stock clocks - you don't need a more powerful PSU for that.

Btw, living in Norway, the choice of TFX units is near zero - definitely nothing even close to €20, and the others I mentioned are above €60. The BeQuiet I mentioned is one of very few models available; other than that there are some brands I've never heard of and thus wouldn't use (you don't buy a garbage PSU. Ever.), a Seasonic at a similar price and a Silverstone at about 3x the price (more than €150). And given that none of the available models have PCIe connectors, none of them are particularly attractive. In short, the choice of the MeanWell was a very thoroughly researched and informed one; there were other options, but none as good, and all with more serious compromises required than what I have made. My solution was more difficult to implement in some ways, though not in others (far less cutting into the case!), but ultimately more than worth it IMO.
 

Valantar

Shrink Way Wielder
Original poster
Jan 20, 2018
1,890
1,822
wow!! I like this very much :)

I'll read it all later, but this is looking really nice
i'm inspired
Thank you! Hopefully there'll be another update this week with more in-use testing - I'm in Sweden again, and had to send the PC in the mail, which of course lead to a bunch of customs nonsense, but it should arrive tomorrow or the day after. Hopefully still working :p
 
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