Is it ok to have an underpowered PSU for 2 GPUs if the second one is never used for rendering?

Posted by Odd_Bumblebee_3631@reddit | buildapc | View on Reddit | 9 comments

So im looking into building a PC and my current PC has a 400W PSU and an ATIHD4890, this beefy but old card requires 2x6 pins.

I use this PC mostly for emulation and old games etc, my steamdeck is for high powered stuff atm.

But im thinking of changing that and building a PC, iv seen a MSI B450 Tomahawk Max Motherboard ATX going fairly cheap and was thinking of pairing that with an RTX 2060 for modern gaming. Now would it be an issue for me to also run the ATI HD4890 in there, normally running a 190W card and a 160W card on a 400W PSU(My current PSU) is really dumb. But considering ill only be using the 4890 to output S video and render on the 2060 would it be ok? What about switching between them depending on if im playing on my big CRT TV or modern games on my monitor.

[-]

Mud-Butt1@reddit

Consider the following, the HD4890 can spike \ peak at 220w and the RTX 2060 is listed for 200w peak you have no overhead room for the rest of your system or for a scenario when your CPU spike on usage.

You should always consider the power draw from your CPU, RAM and rest of the system component. Most gaming computers at idle can be sitting at 80-120w draw. Maxing out your PSU capacity and when considering your PSU is old it would be a matter of time until the voltage dips and your system crashes or starts to get unstable.

Depending on the CPU you decide to use, you should take the peak value of the GPU & CPU and add another 20% as safety factor to your overhead. for example, 220+200 for GPU's = 420. + 125w for AMD CPU = 545w x 1.2 = 654w. So 650w is the minimum PSU size you would want.

Also, I see no reason to keep the HD4890. It draws way too much power for the performance you will get in comparison from the RTX2060.

[-]

Odd_Bumblebee_3631@reddit (OP)

In anycase ill have a look at 650W psus and see what I can get.

[-]

Mud-Butt1@reddit

I would suggest using a signal converter from VGA\HDMI\DP to S-video and remove the HD4890 from your system.

[-]

Odd_Bumblebee_3631@reddit (OP)

Digital to analogue converters bring in all sorts of problems in retro games such as lag, quality loss and as modern cards dont support interlacing they create a bad picture at 480i/240p.

[-]

Odd_Bumblebee_3631@reddit (OP)

The HD4890 is the last GPU that has S video out, I need that for my TV cos I prefer to run 480i natively not play about with converting HDMI to vga to then downscale 480p to 480i and have it look terrible. Im also not a fan of CRT emudriver.

[-]

Mud-Butt1@reddit

You can literally but a conversion box or USB capture card which will give you S-Video output instead of running that old card.

https://www.amazon.com/Capture-Converter-USB-Convert-Camcorder-Compatible/dp/B0CB6BW6X4?crid=2Y1DQGT6VOH8T&dib=eyJ2IjoiMSJ9._JXFCXy0nVkruyub7B5ypHQhTZNRbB7a63VcANy3g4s8sSvUfP4WLO-h8kdzVcwf41EBSB6fVAylC_aRpwOBPz3wEwjEjVixKD40XL5q6q6WodEe6KAVb24YngKg2HQjXIVcw94JWlwqJBGD4dXtxor53Lf6g_VrXfIEipqi3TdkCcJjedt4kRHy5ILZ3b3BarOuWj2omJqO1fQ9FDizHRnzq98oJLWHqHwr3pqXBJw3ed10_i2C6Jpyj8Zf3Ugto1YkpI0Jwf_sudpO1-d6EIvQygUDUHfyilT3bRWhBp8.gf2ad0lW3jvhn3WSrRUXZTdkqbR9TjlEF19CnXRtDPM&dib_tag=se&keywords=S-video+USB&qid=1779474657&s=electronics&sprefix=s-video+usb%2Celectronics%2C178&sr=1-3

[-]