Game PC

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Revision as of 11:05, 13 March 2012 by Lundman (talk | contribs) (HD6670 Dual Graphics)

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Gamer PC

Built a small Gamer PC with the kids, so I guess the main goal was small, quiet. I am also pretty "burnt out" on the last PC we had with all the heating problems. Anyway, this is what I learnt:


  • ASUS F1A75-I Deluxe, Mini-ITX motherboard.
  • AMD A8-3870k CPU (4-core 3GHz CPU, with integrated Radeon HD6550D)
  • Corsair memory (2x 4GB sticks at 1866, total 8GB)
  • JMAX JX-FX500B Mustardseed Mini-ITX case (400W SFX PSU, 12v1 17A, 12v2 16A)
  • SSD for Windows 7x64
  • 1TB Samsung Green HDD for Games
  • Radeon HD 6670 PCIx discrete video card (Dual Graphics / CrossFireX - more on that below)


The initial build was easy, and setup straight forward. You could actually stop here, and just use the Integrated A8-HD6550D graphics for some gaming.

Minecraft-1.2.3: Runs beautifully, all defaults
Modern Warfare 3: Runs beautifully, all defaults
Skyrim: Playable, game picked "High Quality", I would probably lower it if I were to play
NeedForSpeed-TheRun: game looks very nice, but seem to run at half game speed. Audio cuts out at times. Playable, but not ideal.

Did a whole heap of research here to see if I had enough power to run a Radeon HD6670 card, at first on its own, then in CrossFireX (takes more power). Some WWW pages said (33A, 500W!) and others 293W (At least 6A on 12v). So quite conflicting. Luckily the JMAX case had 2 rails for 12V, one goes into the motherboard, and the 2nd to the discrete HD6670 card. Still, why not try:

Radeon HD6670

I could not get "Dual Graphics" to work initially (CrossFireX) so I just tested the HD6670 card on its own. With monitor attached to the HD6670 (discrete) card, I tried out the games again.

NFS-TheRun: Considerably better, it now became apparent that it was running at half speed before, as it is very fast, very smooth to play. No audio drop-outs. 

You can hear the fan on the HD6670 when gaming, but it is not bad. When not gaming, the PC is silent.

Attempting Dual Graphics.

A8-HD6550D Dual Graphics

So there were some fiddling needed here. If I put the monitor on the discrete HD6670 card, I got no signal, or, depending on BIOS setting, I only get the HD6670 card and no integrated HD6550D card.

Main GFX-
BIOS Setting    Monitor-Attached     Outcome
PCIx            HD6670               Only sees HD6670
PCIx            HD6550D              No signal
iGXP            HD6670               No signal (Should be this one)
iGXP            HD6550D              Success

But, this was a lie. More on that in a bit. Finally the [AMD Catalyst Software Suite] (V12.1) added the "AMD Dual Graphics" options to the "Performance Tab". It was odd that the monitor is connected to the A8-HD6550D output, but it did at least work. I fired up NFS again

NFS-TheRun: Running full speed, but with pretty bad slow downs when more cars are around. Some audio drop-outs.

Since I was mainly using the integrated HD6550D, with extra boost from the HD6670 card, it sort of makes sense. It did a little better than just the HD6550D, but not as good as the discrete HD6670 can do on its own.

The AMD Catalyst Software Suite program lets you create profiles for games, where you can disable AMD Dual Graphics for a specific game. But the problem here is, when I do that for NFS, it will only use the integrated HD6550D card, which does not quite cut it. We want to use the HD6670 card as minimum after all, so...

HD6670 Dual Graphics

In trying to solve this, I noticed the driver version for integrated HD6550D (in Device Manager) was a lower version than the discrete HD6670 card I just added. So you really have to uninstall the old card's drivers after all. I clicked Uninstall on the HD6550D, (with 'delete files', or they just got picked again). Then I installed the [AMD Catalyst Software Suite] drivers again. Now device manager confirmed both cards with identical driver version.

Set BIOS to iGXP (otherwise the integrated card gets disabled). Attach monitor to discrete HD6670 card. Making sure to unplug the integrated video connectors. Boot.

There is no BIOS prompt (that goes to the integrated feed) so you are booting 'blind'. But once it boots to the Windows login screen, the discrete HD6670 video pops up. Bonus, the AMD Dual Graphics option is now available. Hurrah!

NFS-TheRun: Runs beautifully again, no slow downs or audio drop-outs.

It is at least as good as just using the discrete HD6670 card. Probably faster, but I would need to run actual benchmarking to confirm that.

Now if I were to disable AMD Dual Graphics for a game, it would then use just the discrete HD6670 card, which is what we want. I have not found any reason to do so. (Since NFS runs better than ever). Skyrim changed to "Ultra High" settings and it flies. Mass Effect 3 = gorgeous.

PSU is still holding on, the system is at 23C when idle, and 45C when gaming.

This combination is then called a Radeon HD6690D2