[SOLVED] Pick a used GPU to upgrade my system

[jamieWakeham]

I've a quite old set-up: Asus P6T mobo, Core i7 920, 3 x 4GB Corsair Vengeance RAM. The current GPU is an NVIDIA 9800GT.

I only game lightly and with older titles - this has been quite good enough to run Quake 4. But I'd like to run some slightly more modern titles - things like the 2016 release of DOOM, for example. As I understand it the GPU is the only thing in my way.

I'm aiming for the most cost effective GPU upgrade, hoping to spend less than £100. I've had a look at what's available from a reasonably reliable reseller of used parts and picked out a list of GPUs, all with with 4GB, and compared their price with benchmarks.

GPU	price	benchmark	power
GTX660	£50​	3950​	140W
R9 270X	£55​	4710​	180W
GTX670	£65​	5230​	170W
R9 290	£72​	8090​	275W
GTX770	£75​	5910​	230W
R9 380	£75​	6090​	190W
R9 290X	£85​	8120​	290W
RX 480	£85​	8490​	150W
GTX690	£88​	6000​	300W
R9 380X	£95​	6350​	190W
RX570	£100​	7000​	120W
RX470	£105​	7910​	120W
GTX970	£110​	9570​	148W
R9 Fury	£120​	10020​	275W

Which would you pick? The R9 290 and RX 480 are looking like stand-outs from a price per performance standpoint, but am I missing anything here?

Thanks in advance!

 

[popatim]

Some of those cards are power hungry, which PSU do you have?

 

[tsdobbi]

"As I understand it the GPU is the only thing in my way."

Not really. Your processor will hold you back.

In 2011 I was in your same situation. i7 920 + 9800GT. Picked up a GTX 580 and the performance gains were rather negligible. Looking a benchmarks in games I had for the card on current gen processors at the time like Sandy Bridge (i7 2XXX series). I was not getting those frames in the 580 on my i7 920 (I was maybe seeing a 5-10% increase depending on the game, but it should have been significantly better)

Your processor actually plays a part in graphics processing and on a high level is giving instructions to the GPU and if your CPU can't communicate with the GPU fast enough to maximize the GPU's potential, then you have a bottleneck.

To put this into a metaphor, imagine you have a truck (the cpu) dropping off bricks to a construction crew (the gpu). You have a situation where the truck isn't dropping off bricks fast enough and the crew is sitting idle waiting for more bricks. Adding 50 more construction workers (a more powerful gpu) isn't going to get the overall job done any faster because they are constantly waiting on bricks as they can only work when they have bricks.

That is essentially what happens with older processors and newer GPU's. The CPU simply cant provide instructions to the GPU fast enough to utilize the GPU's maximum potential. So you hit a point where no matter how much additional GPU horse power you throw in your machine. It is limited by the capability of your CPU.


This was solidified when I built a new i7 haswell 4770k based system in 2013 (still using the 580) and the performance on games I already had increased exponentially.

So the thing is I don't think buying a new GPU is going to help you very much on your 11 year old processor. Will you see a bit of a bump? Sure. I wouldn't go any better than any of the $50ish dollar cards. If you picked up that 970 for example, it is not going to perform for you like a 970 would on a more modern platform.

 

[jamieWakeham]

Thanks, both.

Sorry, should have mentioned the PSU. It's a Kolink, 80 plus, 600W, 48A on the 12V rail. With the current 125W card it's using 26A so there's a fair bit of spare capacity.

I assume the more power hungry cards only draw full power when they're being asked to run hard, so almost all the time it'll be way below capacity.

I do appreciate that the i7 920 is old! I understood that at the moment the GPU will be hugely bottlenecking things; I get that a new GPU might not be able to perform to it's maximum as it will make the CPU the bottleneck. There do seem to be people out there running Doom 2016 on this CPU.

 

[jamieWakeham]

I'm leaning toward either the RX 480 or GTX 970, as these look like they'll remain useful for a while and can be incorporated in any future build.

 

[Xbonepcnovice]

Rx 480/580 8gb

 

[hang-the-9]

Check with the seller and see if they will take 10 or 20 off the 970 price, if not then the RX 480 is your best choice for the money.

 

[jamieWakeham]

Thanks. Looks like they are out of RX 480s... I'll see what I can get a GTX970 down to!