Motherboard and RAM for 10 x r9 280x

[zaartix]

Hello to everyone. Want to mine litecoin and altcoins so need your advice.

We are planning to buy 10 videocards XFX Radeon R9 280X (per 5 in each motherboard). So we think about motherboard, ram and power.

Moherboard.
It is important how fast pci-e slots are in motherboard? For example "GIGABYTE GA-990FXA-UD5" have this:
2 slots x16
2 slots x4
1 slot x8

RAM.
Think about 2x4GB in each monerboard. It is important how fast memory working?

POWER SUPPLY.
Most difficult question. Which PSU need for 5 videocards? It is posssible to use 2 or 3 800watt PSU's  for each motherboard?

VIDEOCARDS.
Each card must be alone or it will be better to make crossfire?

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[Wipeout2097]

XFX tends to cheap out on vram speed. You risk low hashrate with that brand of videocards, even with modded bios or force-flashed from other brand.

PCI-e and system ram speed don't really matter. I suggest a Sempron 190 dual-core instead of the usual 145 single-core, for extra $5 or so.

I have an UD3 but I'm not sure how many cards it really supports at mining. In some motherboards, sometimes adjacent slots are disabled or otherwise aren't stable.

As PSU, See if an EVGA Supernova or Seasonic have 10 pci-e connectors, perhaps 1300w and above.

Crossfire is detrimental to coin mining.

[zaartix]

thx for advice.
Which brand is better for videocard?
Asus, GIGABYTE, Sapphire, MSI, PowerColor ?

[atp1916]

Asus tends to be overpriced sometimes.  

Gigabyte 79xx cards had VRM flame-out issues, so i am not sure if that's still a "feature" of the 280x variations.

Powercolor i have heard of general QA issues, like the XFX boards.



My personal vote would go to MSI!

[crazyates]

Gigabyte 970A-D3P - works with 5 cards, and is $85.

AMD Sempron 145 - Cheap, works, and is $45.

Two 800W PSUs. make sure they're a good brand, strong single rail, with enough PCIe connectors, and 80Plus Gold. I'd check out the Rosewill 800W Lightning.

You could go with 2x4GB, but we actually found that a single 8GB stick was cheaper, and works the same. Shop around tho, and whatever's cheapest for you, that's the one to buy!

[zaartix]

thanks to all for replies.

What if i can check videocard before buying? For example start miner on each of XFX board. It is safe to buy it if hashrate will be ok?

[Charloz24]

Question about ram: is 4gb enough? Let's say for 2X 280x videocards?