About Intel Haswell HD Graphics

Question

Recently I bought Intel Haswell cpu (G3420). Right now I am using Intel HD Graphics. Does running graphics adapter slows down cpu? If I add a discrete graphics adapter will I get benefits from running HD Graphics (same as AMD Dual-Graphics) of should I better turn it off?

Answer 1

Using either an iGPU or a discrete card will not affect the performance of the CPU (in isolation). i.e. the CPU will do the same number of calculations per second.

However, overall system performance will definitely vary between discrete and iGPU's especially, obviously, for 3D applications.

If you have a discrete card, it will usually be faster than the iGPU for overall performance unless the card is very old or basic. There is not much downside to using discrete graphics cards, outside of power consumption and heat.

Answer 2

Does running graphics adapter slows down CPU?

Yes, but usually not noticeable.

The iGPU is on the same die as the CPU part. It shares the chips thermal budget. Simply said, if you use the graphics part then the chip gets hotter and has less room to turbo.

In normal usage and with good cooling you probably do not notice any difference though it should show up on benchmarks. If you have poor cooling then it likely makes a bigger difference.

If I add a discrete graphics adapter will I get benefits from running HD Graphics (same as AMD Dual-Graphics) of should I better turn it off?

In all setups prior to DX12 you would gain no performance benefit from running both a dedicated graphics card and the onboard GPU. You do gain the benit that you have more useful monitor outputs, allowing for more monitors to be connected.

Most dedicated cards seem to have about 4 simultaniously usable output ports (and that is ignoring chaining things with DP MST) so this is not likely to be needed, but if you want to connect 6 or 7 monitors then 4 on the dedicated card and 3 on the outputs from the motherboard (powered by the iGPU) is possible.

For completeness sake: The AMD setup you mentioned is usually does work because it is the same type of graphics family and the build in AMD graphics part on their APU's is uaually faster than Intels iGPU's.

Same family is important. Crossfire only works with similar AMD cards (ditto for SLI which needs to identical or very similar Nvidia cards).

There is also some overhead when using two graphics chips, so combining a very fast card with a very slow card might actually perform worse than just using the fast card. With AMDs APU focussing alot of graphics speed this is not an issue when adding a medium AMD dedicated card, but generally Intel iGPU's are less fast.