Crossfire 7970 x4/16

amd_man · May 28, 2013

I have a gigabyte HD3 motherboard which only does x4(2.0)/x16(3.0), I was thinking about crossfiring my 7970, so would it be worth it? My psu is a corsair cx750, would it be enough for my system? corei7 3770k, 8gb ddr3, 1hdd, 1dvd/rw. I am planning on running everything at stock.

DOM · May 28, 2013

What's the res. on your screen ?

kn00tcn · May 28, 2013

http://www.legitreviews.com/article/1834/11/ power seems fine for normal games

what games will you play? crysis3, fc3 seem like the ones that dont handle 60 with fancy max settings even at 1080p

RCoon · May 28, 2013

The x4 slot will throttle the GPU on a fairly small scale, so you'll lose a little performance from there. Without Overclocking, the PSU should handle it just fine. Surprised you have such a decent system and such an average MoBo.
Sure it has XFire support, but I recommend getting a 16x/8x or 8x/8x Mobo at least.

At 1080p probably isnt worth it unless you have a 120hz Monitor.
Higher resolutions, it starts being worth the money.

Aquinus · May 28, 2013

RCoon said:
Sure it has XFire support, but I recommend getting a 16x/8x or 8x/8x Mobo at least.

Don't you mean (16x/0x or 8x/8x) or (16x/0x/4x, 8x/8x/4x)? SB/IVB only has 20 PCI-E lanes off the CPU, you can't do 16x + 8x that's more than 20 and PLX chips will add a heck of a lot more than that. Plus, only 7-series chipsets with an IVB chip can use those last 4 lanes off the CPU for a slot, in 6-series chipsets it was wired to the PCH iirc.

RCoon · May 28, 2013

Aquinus said:
Don't you mean (16x/0x or 8x/8x) or (16x/0x/4x, 8x/8x/4x)? SB/IVB only has 20 PCI-E lanes off the CPU, you can't do 16x + 8x that's more than 20 and PLX chips will add a heck of a lot more than that. Plus, only 7-series chipsets with an IVB chip can use those last 4 lanes off the CPU for a slot, in 6-series chipsets it was wired to the PCH iirc.

The point I was making was to have AT least two x8 lanes or better for PCI-E 2.0, not necessarily saying JUST a 16x and 8x with or without PLX.

blibba · May 28, 2013

PCI-E 2.0 x4 is equivalent to PCI-E 3.0 x2.

It could be quite a severe bottleneck in some games - note the near 50% loss in minimum FPS on Dirt 3.

amd_man · May 28, 2013

Thanks guys so I was looking at these parts : http://secure1.ncix.com/cart/

_larry · Jun 6, 2013

I just ordered a 7950 to take place of my two 7770s in x16/x4. The performance is not up to par with newer games maxed out. However the MAIN reason I'm getting rid of them is because of the stuttering issues. The x16 card has to slow down and hold frames to wait for the x4 card...AMD has been trying to fix this issue for a while and there are rumors it will be fixed soon. Also, nearly every game I have tried to mod develops all types of graphical glitches in crossfire...I highly recommend you stay away from crossfire. ESPECIALLY x16/x4 setups.

OneMoar · Jun 6, 2013

its not a problem with the PCIe buss

http://www.asrock.com/mb/Intel/Z75 Pro3/?cat=Specifications

- 1 x PCI Express 3.0 x16 slot (PCIE2: x16 mode)
- 1 x PCI Express 2.0 x16 slot (PCIE3: x4 mode)
- 1 x PCI Express 2.0 x1 slot
- 2 x PCI slots
- Supports AMD Quad CrossFireX™ and CrossFireX

there is no bottleneck in regards to the Pcie Slots:
PCI3 3.0 X4 is just as fast as PCIe 2.0 http://www.pcisig.com/news_room/faqs/pcie3.0_faq/#EQ2
as for the frame-latency issue with crossfire thats unrelated to the pcie buss

blibba · Jun 6, 2013

OneMoar said:
- 1 x PCI Express 3.0 x16 slot (PCIE2: x16 mode)
- 1 x PCI Express 2.0 x16 slot (PCIE3: x4 mode)
- 1 x PCI Express 2.0 x1 slot
- 2 x PCI slots
- Supports AMD Quad CrossFireX™ and CrossFireX

there is no bottleneck in regards to the Pcie Slots:
PCI3 3.0 X4 is just as fast as PCIe 2.0 http://www.pcisig.com/news_room/faqs/pcie3.0_faq/#EQ2

This is incorrect. The slots are 16x3.0 and 4x2.0. 4x2.0 is as fast as 2x3.0, which is significantly slower than, for example, 8x2.0.

Aquinus · Jun 6, 2013

Can we just agree that: Yes, he can run crossfire but no it won't be flawless and run at full speed as if he had two full 16 lanes. It will work well, yes. Perect? No.

blibba · Jun 6, 2013

Aquinus said:
Can we just agree that: Yes, he can run crossfire but no it won't be flawless and run at full speed as if he had two full 16 lanes. It will work well, yes. Perect? No.

I'm certainly up for that!

silkstone · Jun 6, 2013

If he were to crossfire his 7970 with a 7870 (tahiti) what would the performance be like compared with 2x 7970's on those lanes?

I ask as my mobo has only 16x + 4x and, although i'm not planning on running crossfire right now, I'd like to know what my options would be in the future.

blibba · Jun 6, 2013

silkstone said:
If he were to crossfire his 7970 with a 7870 (tahiti) what would the performance be like compared with 2x 7970's on those lanes?

I ask as my mobo has only 16x + 4x and, although i'm not planning on running crossfire right now, I'd like to know what my options would be in the future.

As I understand it, while 7970+7930 would yield higher FPS than 7930+7930, the "smoothness" would be the same as 7930+7930. Someone correct me if I'm wrong.

So basically, if that's the case, you might as well run 7930+7930 in any given lane configuration.

If I were you and my 7970 was no longer cutting it, I'd sell it and buy a factory OC GTX780 or a dual-GPU card (690 etc.).

OneMoar · Jun 6, 2013

blibba said:
This is incorrect. The slots are 16x3.0 and 4x2.0. 4x2.0 is as fast as 2x3.0, which is significantly slower than, for example, 8x2.0.

http://www.asrock.com/mb/Intel/Z75 Pro3/?cat=Specifications
not according to the specs
its X4 3.0 =/= X16 2.0

blibba · Jun 6, 2013

OneMoar said:
http://www.asrock.com/mb/Intel/Z75 Pro3/?cat=Specifications
not according to the specs
its X4 3.0 =/= X16 2.0

When it says:
- 1 x PCI Express 3.0 x16 slot (PCIE2: x16 mode)
- 1 x PCI Express 2.0 x16 slot (PCIE3: x4 mode)

it means that the 2nd PCI-E slot is x16 (aka PCIE2), and the 3rd PCI-E slot (aka PCIE3) is x4. But something tells me that you know that.

OneMoar · Jun 7, 2013

blibba said:
When it says:
- 1 x PCI Express 3.0 x16 slot (PCIE2: x16 mode)
- 1 x PCI Express 2.0 x16 slot (PCIE3: x4 mode)

it means that the 2nd PCI-E slot is x16 (aka PCIE2), and the 3rd PCI-E slot (aka PCIE3) is x4. But something tells me that you know that.

you said that slot2 was pcie 2.0 x4
both slots are 2.0 x16 effectively
X4 3.0 is the same as 2.0 x16

blibba · Jun 7, 2013

OneMoar said:
both slots are 2.0 x16 effectively
X4 3.0 is the same as 2.0 x16

That's just not the case. Where are you getting this from?

Firstly the second slot is 2.0x4, not 3.0x4, and secondly 2.0x16 does not equal 3.0x4.

https://en.wikipedia.org/wiki/PCI_Express

OneMoar · Jun 7, 2013

blibba said:
That's just not the case. Where are you getting this from?

https://en.wikipedia.org/wiki/PCI_Express

its not ?
from
http://www.pcisig.com/news_room/faqs/pcie3.0_faq/
PCIe 3.0 x4 has a total of 16GB/s bothways way
both ways would be 8GB/s (one way) or X8 2.0 with his cards it doesn't matter because they can't saturate a 8GB/s link either way
http://www.techpowerup.com/reviews/Intel/Ivy_Bridge_PCI-Express_Scaling/12.html
even with a 7970 it doesn't matter

blibba · Jun 7, 2013

OneMoar said:
its not ?
from
http://www.pcisig.com/news_room/faqs/pcie3.0_faq/
PCIe 3.0 x4 has a total of 16GB/s bothways way
both ways would be 8GB/s (one way) or X8 2.0 with his cards it doesn't matter because they can't saturate a 8GB/s link either way
http://www.techpowerup.com/reviews/Intel/Ivy_Bridge_PCI-Express_Scaling/12.html
even with a 7970 it doesn't matter

That's largely true, but not what you were saying.

Aquinus · Jun 7, 2013

You two really need to give it a rest. Either way, it should work fine in most cases. So regardless of what the number are, it will still work.

Also I notice someone say that 4x 3.0 is the same as 16x 2.0. That's not true. From a bandwidth perspective, 2.0 to 3.0 doubles bandwidth, so 4 lanes at 3.0 is more like 8 lanes at 2.0.

blibba said:
Firstly the second slot is 2.0x4, not 3.0x4

ASRock's site is a little wonky with those specs, but I suspect that both slots are capable of 3.0 considering how it's written and what the CPU supports.

silkstone · Jun 7, 2013

My specs say: 2 x PCI Express 2.0 x16 slots (PCIE2 @ x16 mode; PCIE4 @ x4 mode)

My first slot is PCIE 2.0 x16, the second is PCIE 2.0 x4

The part in the brackets (PCIE2) denotes the slot number, i think. -I think this is where the confusion is coming from "PCIE3 x4" means the 3rd PCIE slot works in x4 mode.

so, according to specs, he has 1x PCIE 3.0 x16 and 1x PCIE 2.0 x4

Processor	Intel i7 4770K
Motherboard	Asrock
Cooling	Water
Memory	Team Xtreem LV 16GB (2x8GB)
Video Card(s)	EK Full WB HD7970
Display(s)	CROSSOVER 27Q LED-P 27"
Case	Danger Den Torture Rack
Audio Device(s)	Onboard
Power Supply	CORSAIR Professional Series Gold AX1200
Software	W 10 Pro

System Name	HP Omen 17
Processor	i7 7700HQ
Memory	16GB 2400Mhz DDR4
Video Card(s)	GTX 1060
Storage	Samsung SM961 256GB + HGST 1TB
Display(s)	1080p IPS G-SYNC 75Hz
Audio Device(s)	Bang & Olufsen
Power Supply	230W
Mouse	Roccat Kone XTD+
Software	Win 10 Pro

System Name	Apollo
Processor	Intel Core i9 9880H
Motherboard	Some proprietary Apple thing.
Memory	64GB DDR4-2667
Video Card(s)	AMD Radeon Pro 5600M, 8GB HBM2
Storage	1TB Apple NVMe, 4TB External
Display(s)	Laptop @ 3072x1920 + 2x LG 5k Ultrafine TB3 displays
Case	MacBook Pro (16", 2019)
Audio Device(s)	AirPods Pro, Sennheiser HD 380s w/ FIIO Alpen 2, or Logitech 2.1 Speakers
Power Supply	96w Power Adapter
Mouse	Logitech MX Master 3
Keyboard	Logitech G915, GL Clicky
Software	MacOS 12.1

System Name	HP Omen 17
Processor	i7 7700HQ
Memory	16GB 2400Mhz DDR4
Video Card(s)	GTX 1060
Storage	Samsung SM961 256GB + HGST 1TB
Display(s)	1080p IPS G-SYNC 75Hz
Audio Device(s)	Bang & Olufsen
Power Supply	230W
Mouse	Roccat Kone XTD+
Software	Win 10 Pro

System Name	The one under the desk / Media Centre
Processor	Xeon X3730@3.6GHZ / Phenom II X4 805E
Motherboard	Gigabyte P55M-UD4 / Asus Crosshair III
Cooling	Corsair H70 + 2*PWM fan / Arctic Alpine 11
Memory	16GB DRR3-1333 9-9-9-27 / 4GB Crucial DDR3-1333
Video Card(s)	Asus DirectCU GTX 680 / Gigabyte 560TI
Storage	Kingston V200 128GB, WD6400AAKS, 1TB Seagate 7.2kRPM SSHD / Kingston V200 128GB
Display(s)	Samsung 2343BW + Dell Ultrasharp 1600*1200 / 32" TV
Case	C'M' Silencio 550 / Some ancient SilverStone brushed aluminium media centre
Audio Device(s)	No.
Power Supply	Thermaltake Toughpower XT 675W / EVGA 430W
Mouse	Mionix Naos 3200 / Generic PS2
Keyboard	Roccat Ryos TKL Pro / Evoluent Mouse Friendly Keyboard (Logitech OEM)
Software	Windows 7 Ult x64
Benchmark Scores	Nah.

Crossfire 7970 x4/16

amd_man

New Member

DOM

kn00tcn

RCoon

Aquinus

Resident Wat-man

RCoon

blibba

amd_man

New Member

_larry

OneMoar

There is Always Moar

blibba

Aquinus

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blibba

silkstone

blibba

OneMoar

There is Always Moar

blibba

OneMoar

There is Always Moar

blibba

OneMoar

There is Always Moar

blibba

Aquinus

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silkstone

System Name	RYZEN RECKER
Processor	Ryzen 5 5600X
Motherboard	Asus Prime B350-plus
Cooling	Arctic Cooler 120mm CPU, Cougar case fans.
Memory	16GB (2x8GB) Corsair LPX 3200mhz
Video Card(s)	XFX 6700XT Swift 309
Storage	6.5TB total across 4 different drives
Display(s)	Acer 32" 170hz VA
Case	Antec 900
Audio Device(s)	Logitech G430 headset
Power Supply	Corsair CX850m
Mouse	Steel Series Sensei Ten
Keyboard	Corsair K55
Software	Windows 10 64-bit

System Name	RPC MK2.5
Processor	Ryzen 5800x
Motherboard	Gigabyte Aorus Pro V2
Cooling	Enermax ETX-T50RGB
Memory	CL16 BL2K16G36C16U4RL 3600 1:1 micron e-die
Video Card(s)	GIGABYTE RTX 3070 Ti GAMING OC
Storage	ADATA SX8200PRO NVME 512GB, Intel 545s 500GBSSD, ADATA SU800 SSD, 3TB Spinner
Display(s)	LG Ultra Gear 32 1440p 165hz Dell 1440p 75hz
Case	Phanteks P300 /w 300A front panel conversion
Audio Device(s)	onboard
Power Supply	SeaSonic Focus+ Platinum 750W
Mouse	Kone burst Pro
Keyboard	EVGA Z15
Software	Windows 11 +startisallback

System Name	Gaming System / HTPC-Server
Processor	i7 8700K (@4.8 Ghz All-Core) / R7 5900X
Motherboard	Z370 Aorus Ultra Gaming / MSI B450 Mortar Max
Cooling	CM ML360 / CM ML240L
Memory	16Gb Hynix @3200 MHz / 16Gb Hynix @3000Mhz
Video Card(s)	Zotac 3080 / Colorful 1060
Storage	750G MX300 + 2x500G NVMe / 40Tb Reds + 1Tb WD Blue NVMe
Display(s)	LG 27GN800-B 27'' 2K 144Hz / Sony TV
Case	Xigmatek Aquarius Plus / Corsair Air 240
Audio Device(s)	On Board Realtek
Power Supply	Super Flower Leadex III Gold 750W / Andyson TX-700 Platinum
Mouse	Logitech G502 Hero / K400+
Keyboard	Wooting Two / K400+
Software	Windows 10 x64
Benchmark Scores	Cinebench R15 = 1542 3D Mark Timespy = 9758