Dunlop0078 :
cdrkf :
knight1122 :
Hi and good day to you all.
I am here to get some helpful opinions about the upgrade that I am thinking of for my PC.
I currently have
Intel Core i5 2400 processor
with 4 GB of DDR3
and a Powercolor HD 7850 2 GB
running on an 850 watts PSU that is "Cooler Master RS-850-EMBA".
I want to know if I exchange the HD 7850 with a Sapphire R9-290 4GB GDDR5 TRI-X OC, will that PSU hold it's ground or am I gonna run into problems concerning "Wattage" for that power hungry beast that is R9-290? (Also, an extra 4 GB RAM stick is gonna be added).
Many thanks in advance for all your help and time.
Regards;
Knights.
I've looked up that PSU and I'm not sure it will play nicely with a 290. It's got lots of low current 12v rails rather than the preferable option which is 1 higher current output rail.
At only 18A per +12v rail it's probably not enough to keep a 290 happy under heavy load. I'd suggest looking into something from Seasonic with a single +12V rail with at least 40A of current delivery.
Dont worry that cooler master psu will be fine.
You should look up the difference between single and multi rail psu's. Multi rail psu's are better for the most part and certainly safer, in the US people like to say single rail power supplies are better for some reason, marketing mostly. Check out this video on it.
https://www.youtube.com/watch?v=PWtKSHT2od8
Well a lot of cheap 'oem' multi rail PSUs *aren't* up to it irrespective of the wattage.
The issue comes down to basic electronics, if you have 2 separate current sources, unless the voltages on the 2 sources are *perfectly balanced* then all the current will get drawn from 1 source. As a result using 2 x 18A rails to power a single device is likely to function as 1 x 18A rail- which for a 290 isn't enough.
Now, there are some 'multi rail' PSU's that are actually built as a single high current source and split into multiple outputs. This is fine, although it then begs the question why would you limit each output to only 18A.
A nice single rail supply with a high output (e.g. 40A+) will pretty much run anything and there's no issue with balancing. I personally wouldn't trust this supply with a 290 without being able to find considerably more information about it's internals.
I'm saying this as a product designer who works on electronics including power supply design. Multi rails are usually a way to get a high total wattage value with cheaper components and is a typical sign of OEM Chinese stuff. There is a good reason why high current single rail is preferable, it's also more expensive because it requires high quality components to deliver 40A than it does to deliver 18A.
Now high end multi rail supplies are fine, although they are built to drive multiple cards, and usually have multiple rails of 30 - 40A each (with 1 rail being fed into 1 card).
Edit: For your video- they have a 1000W *single rail supply* with a current limit that can be turned on / off in software. That design also gives you 40A of power per rail, more than enough for a high end card. 18A per rails is *too low* for an R9 290. It's not a comparable situation.