[SOLVED] Sharing APU VRAM with GPU

[ShinChuck]

Strange, possibly dumb question: if my APU can use 4 GB RAM as video RAM, can I somehow share that RAM with my 2GB GPU to give it 6GB to play with?

To elaborate: I have an ASUS Zenbook 14 Q407IQ-BR5N4. It has an AMD Ryzen 5 4500U 2.3 GHz processor, an MX350 2GB GPU, and 8 GB RAM. I'm trying to do some light gaming, and while the obvious solution is to buy a better laptop, I got a great deal on this one, I'm on a tight budget, and I'm basically stuck trying to milk it for every FPS it's worth.

For the most part, the MX350 earns me a 5-10 FPS gain compared to the APU on low settings for reasonably fancy games, taking some games from 25 to 35. For example, Resident Evil 7 goes from a rough 20-something to a consistent 30-something at 1080p on low settings while utilizing the MX350; nearly the difference between playable and unplayable. Older games like Guild Wars 2 have also had some nice boosts when using the GPU over the APU.

The problem is that heavier games actually perform better with the MX350 disabled! Resident Evil Village at low settings and 1080p runs at about 21 FPS with constant slowdown on the MX350, but does 30+ on the same settings on the APU, going from an unplayable to relatively comfortable experience. The in-game settings claim 4 GB of video ram is available when I use the APU (as opposed to the mere 2 when using the GPU), and I assume that's what making the difference, since otherwise the GPU is preferable. In my head, it seems like if the APU can utilize 4 of the 8 GB as RAM, then the GPU should be able to use it's own 2GB plus the same four GB the APU can use.

All the same, I know enough to know that "seems like" means little! Right now my only option is to judge whether to use the APU or GPU on a game-by-game basis, which is less than ideal, and seems pretty inefficient. I poked around in the bios and didn't see anything immediately irrelevant.

Am I asking for something that's not feasible? Any way to pull this off, or other suggestions or tricks? Believe me, I'd love to get a nice gaming laptop, but for now, it's squeeze everything I can out of this guy or nothing!

Thanks for any help, and sorry if this is something that's been covered that I've overlooked!

 

[rgd1101]

apu vram is system ram.
and no.
lower the game detail. are the game running in directx11 on apu and on mx350?

 

[ShinChuck]

Thanks much for the response, and sorry for the delay! It was a few days before I could play with my laptop again.

From what I'm reading, RE8 requires Direct X12.

The problem isn't that the game is unplayable itself, it's just that it's playable on the APU with the system RAM acting as its VRAM but not on the GPU. We're talking even on the lowest settings, the APU is superior. It's such a strange situation where the APU + System Ram runs a game better than a slightly superior GPU with it's own, but smaller, pool of RAM. I was expecting that I couldn't share the system RAM with the GPU, but was hoping maybe there was some way of jerry rigging it; ah well!

I guess I'll just have use either APU or GPU on a game by game basis. For the most part, the GPU does earn me an FPS boost, but resource-heavy games like RE8 that recommend a minimum of 4 GB VRAM will probably run better on the APU, I suppose!

 

[JWNoctis]

Your APU certainly had more memory bandwidth, once you get above 2GB - Shared system memory as VRAM over PCIe, which your MX350 does use if required, is considerably slower, and some games might be sensitive to that, as you've seen.