Matching CPU to GPU capabilities.

How do you know what video board to buy in order to match the capabilities of your CPU such that neither is a glaring weak link. In hours of searching I’ve found a lot of comparisons of one GPU to another, as well as a listing or their texture fill rates and whatnot, but not an answer to the obvious question for a lot of people. Specifically I’m looking for what GPU I need to match a Core i5 2500K at stock clocking, but a general answer might be helpful to a lot of people. Taking a wile guess I was thinking a Radeon 7850, since that’s the same upper midrange category as the CPU, but I really have no idea.

Is this for gaming? If so, the video card will almost certainly be the weak link no matter what you buy. I know I didn’t quite answer your question, but the concept of “matching” is ill-defined without more context.

Yes, it’s for gaming. Is that why two GPU setups are so popular? Specfically I want to run the Sims 3 at 1680 pixels with the quality settings maxed out, but I might want to run other games too in the future.

The CPU is fairly capable, and the system requirements for Sims 3 is a “128 MB Video Card with support for Pixel Shader 2.0”, which is pretty low. Even a $40 card is going to easily surpass that.

Here is the breakdown and ranking for currently available cards from Tom’s

I think you are going to get a lot of bang for your buck in the 100 -150 range without getting into a loud, hot, and expensive high end card.

Yeah, I’ve heard even the integrated Intel HD3000 graphics will run the Sims 3. I want to run it at maximum settings, as opposed to the minimum required to get it to load and run.

So if it’s not realistically possible to buy a GPU such that it’s not the bottleneck in games, is marketing mid to high end CPUs like the i5 and i7 kind of a scam then?

I’ve seen multiple opinions that the i5-2500 is the ceiling right now for game performance and the only reason to get an i7 is for specialized tasks. I don’t know if it’s a “scam” since it’s useful for high end media tasks (film rendering and stuff) but it’s more than you need to play games on. The real scam would be stores trying to convince buyers that you need the top model CPU to play games.

Ten to fifteen years ago you (well, I) had to be a lot more careful in building a system and selecting components. This board works with that series of graphics cards (whoa, just had a Voodoo 3 flashback!), sound card had to be one of several, chipset determined a lot, etc. I may be off a bit now through foggy memory, but you used to need to spend time making sure that everythign worked together. Now? There are outliers, but I can’t imagine a stock graphics card having problems with a stock mobo/CPU.

Ah, to go back to 80386!

I remember those days. Setting IRQ and IO addresses with jumpers and dip switches. Trying to get a Gravis Ultrasound to work. Paying $180 for 4 megs of Ram. Thinking how cool The 7th Guest and Doom were.

It’s better to match the GPU to your screen, not the CPU. CPUs are essentially threshold devices when it comes to games; it’s either good enough (can sustain 60 fps) or it’s not. There’s generally nothing you can dial back in case you aren’t fast enough. Of course, powerful CPUs are good for non-gaming tasks.

So the important questions are:

  • How many pixels does your screen have?
  • What kinds of games do you play?
  • What do you consider an acceptable frame rate?
  • Do you care about having all the graphical goodies, like anti-aliasing, anisotropic filtering, and the “ultra” settings in your game?

A 1920x1080 screen running modern games at 60 fps requires a fairly beefy GPU.

Of course, you can always dial down the resolution if you aren’t hitting an acceptable framerate. However, scaling still doesn’t look at great on LCDs, and so ideally you run at the native res. And of course it’s nice to have the extra goodies, especially since they give you headroom for when even more demanding games come out.

I have a 1680*1050 screen, I like to run it at native resolution and with as much anti-aliasing and shadows and stuff as possible enabled, I haven’t really thought of what games I want to play other than my sister playing Sims 3, but gaming is something I might want to get back into, I used to play the Call of Duty series a lot. Generally I like to get 45 frames a second or better.

One thing I didn’t see mentioned yet is that quite a few of the “standard desktop systems” from the big-name manufacturers can’t actually accommodate top-end video cards. As a specific example, Dell systems tend to have only one PCIe x16 slot, and it is all the way at one end of the system board. There’s no slot opening for a card that uses a 2-slot bracket, and the CPU heat sink (Dell is a big fan of large, passive heat sinks instead of fans) takes up the same space as the board and fan of the video card.

For various reasons, there are very few single-slot high-end video cards with small fans, at least in the Radeon family (which is what I’m most familiar with). A HD 5750 or 5770 is typically the fastest card that is generally available in that config. There are some HD 68xx cards and (apparently) a forthcoming HD 7850 card that are single slot, but they’re still too long to fit in the average Dell.

The most popular page on my blog contains many, many comments from users asking about putting faster video cards in Dell systems.

If you go with a system designed for gaming (from Dell or anybody else), it will likely be more accomodating of the larger video cards. But there’s also a good chance that it already has something decent in it anyway.

I think a good general benchmark for a gaming PC is to spend about 1.5x-2.5x the amount of money on your videocard than you are on your CPU, and then follow something like the Tom’s hardware list above to figure out which card to select. If your budget doesn’t allow for this, you should probably scale back on your CPU selection until it does.

As others have said, the gpu is almost always the limiting factor when gaming. My recent rule of thumb is gpu price = cpu + motherboard price. Then after a year or two I might upgrade the gpu with whatever is currently selling at about that same price. That card might come close to matching the cpu, but it wasn’t available at any price when I built the machine.

Ok. I get the idea. Nothing I can reasonably buy can equal the almighty i5.

Another question, my motherboard has 3 Z68 chipset controlled Sata 3GB ports, 2 Z68 chipset controlled Sata 6GB ports, and 2 additional 6 GB ports controlled by a Marvell chip that’s connected to the PCI-Express bus.

I have a SSD, a 7200 RPM Hard Drive, and a Blue-Ray reader. I assume I want the SSD on one of the 6GB ports, (is it better if it’s one controlled directly by the chipset) but does it matter where I hook the others up?

Wait, what? Am I reading this right? I put a pair of 5770s in a build I did back in 2009. They’re still holding value? Still the eighth tierat Tom’s?

Something just feels … wrong. What am I missing?

Dropping seven tiers in 2.5 years seems reasonable to me. If you need a single-slot card it’s as good as you’ll find, but without that restriction it wouldn’t be in the running.

I had a 5770 but it was grossly unrelable, so I replaced it with a 5670
I found the tiers really useful- I figured out much would cost to go up each tier, and then stopped when the incremental improvement was more than $100. I wound up ordering a 6950, which I got an 8% coupon code and $30.00 rebate on. Seems like the current AMD cpus are garbage, but they still make decent graphics cards so I can at least throw that business their way.