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Hey guys,
I needed to build a small-as-possible, quiet computer for light gaming (Rocksmith, Dark Souls, Divinity, Diablo) and tossed together some used parts off of eBay. I also wanted to keep it under 400 Euro including the 256 GB SSD, so I went with an APU.
I've spent 320 € on this build so far, so I have 79 € left for RAM:
AMD A10-7800 Gigabyte F2A88XN-Wifi Samsung Pro 840 256 GB Noctua N9L-a Fan Lian Li PC Q12 Leftover 2,5" 5400 RPM HDD from my external enclosure (not included in the 400 €).
I have read a couple of times that you should aim for 2400 MHz ram with an APU, but is that even supported? I might also want to upgrade to a larger cooling solution and the next generation of highend APUs, so RAM height might be an issue.
Thanks for the help!
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RAM speed really doesn't matter on your rig, but try to keep it 633 or above.
And your crazy 70$ 4GB ultra gaming megay420mlg RAM stick will perform the same (sometimes worse from part skipping etc) as a $25 RAM stick. Just buy whatever size you need (I personally have 4GB and can max SC2 on it). With all that leftover money you might want to get 8GB stick.
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So you recommend getting a single 8 GB stick, no matter the frequency?
Should you be giving advice here? I'm clueless about this sort of thing, but Anandtech and TomsHardware both report that dual channel is vital and that RAM frequency matters a great deal in APU builds, because the RAM acts as both the system RAM and the vRAM.
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On the contrary, for APU's the speed for RAM does effect performance somewhat significantly. If I recall correctly, 1800MHz was about the sweet spot for APU performance. the higher the MHz, the higher the latency I believe. so I wouldn't go above the 2400 MHz that you suggest but somewhere from 1800-2400 MHz should be fine.
Also, I think you would be better served going with a 2x4gb configuration to increase your bandwidth. (less sure about this than the previous statements)
I think Linustechtips did a video on this. I'd look for that and see what they concluded.
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The frequency one was the least of my concers, I felt like I had a good grasp of that already.
According to tests done at Crucial, the sweet spot is 2133 MHZ, though others report you can benefit from 2400. I'll go with 2400 regardless.
What I need help with is a specific model that has the right timings and voltage for the mainboard I'm getting. The mainboard is the only part I'm buying new, so if it's not the ideal component, I can still change that.
For instance, the documentation says that the F2A88XN supports 1,5v RAM. Does that mean 1,65v RAM won't run? Or that it has slower performance? It says it supports ram up to 2400 MHz, but I don't find any that is 2400 MHz and not 1,65v.
That's the only part that's missing from my build and it's getting really frustrating using my phone as my main computer.
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Thanks for that link, it's incredibly hard to do proper research on a 4" screen without being able to even copy and Pete properly.
A bunch of the ones they recommend have 1,65v so I guess it's fine. I'm going with the AMD one because that's the only one that doesn't have a grotesquely large cooler, even though it's 10€ more and will push this build to 402 €.
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United Kingdom20154 Posts
RAM performance does matter for an APU, because the iGPU is fed by the RAM.
the higher the MHz, the higher the latency I believe
1600c8 and 2400c12 have the same latency. The cas latency is measured by clock cycles - so while 12 cycles is 1.5x more than 8 cycles, the 2400mhz is cycling 1.5x faster than 1600mhz so the functional latency is the same, but bandwidth 1.5x higher.
You should get ~2133c9-2400c10 ish RAM if possible. You should always get two sticks to run in dual channel or you'll see significant performance degradation.
I think Linustechtips did a video on this. I'd look for that and see what they concluded.
They might have done several. The last one i saw they were testing RAM on a bunch of games without system RAM scaling on a non-APU and concluding that there was no benefit; which is true a lot of the time - but it's not true for those games that do scale with system RAM performance (starcraft 2 is one of them) and when you're using that system RAM as VRAM for iGPU (like for an APU)
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In addition to RAM speed, the CAS latency of the ram is also very important Poor 2400 RAM with 11 CAS are actually generally outperformed by 2133 ram with tighter timings, generally the sweet spot would be some sort of 2133 CAS9 ram In terms of real life performance in APU, having a 2x4 will almost always outperform 1x8 as well
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Now I'm thrown off again, fuck. The one I picked out was 2400/11.
Can anyone do me a solid and pick out a proper one from idealo.de or Geizhals.de? Doing this on my phone is driving me NUTS!
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United Kingdom20154 Posts
c11 @2400 is still alright. You don't have to be that anal about it when different RAM has different performance anyway depending on the IC manufacturer/type that you won't really be able to know unless you're a RAM enthusiast. As long as you have the basics right (2 sticks, high frequency)
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All the faster RAMs have a voltage of 1,65v, whereas according to the mainboard specification, the GA mainboard only has 1,5v. Is that a problem?
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No that's fine Power heat and noise will be almost the same. You can likely run at lower timings than spec as well.
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Not sure if you care enough about fps but you possibly overclock the graphics on the spurs well. May help a bit esp with fast ram.
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Well, I decided to go with the 7800, which doesn't have a 'K', so I'm afraid overclocking isn't an option.
I went with 2133 MHz CL9 RAM, 2*4 GB because that was 20 € cheaper than going with 2400-11.
My reasoning is this:
The games I want to play now run on the 7800 just as well as on the 7850, and the only game on the horizon I'm interested in runs on neither. In such a small case I'd rather go with 65w so I can use Noctua's ULN adapters to keep things quit. That's more important to me than marginal FPS increases.
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So the build is finally done, and boy is it tiny.
I added a Noctua case fan because I suspected the stock fan would be too loud and I was right. Do I need to worry about idle temps of 45°? The temps after an hour of Dark Souls 2 on highest setting without frame limiter are barely higher.
Is that just the typical AMD shittiness or is that a cause for concern?
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AMD stuff tends to run hot
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I have a 7700K in one of my media centers and it does indeed run rather hot
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