Gen 4 PCIe on B350

imrazor · February 17, 2023, 9:24pm

After watching @wendell’s latest video…

I started to wonder. There was a brief period where beta BIOSes were available for B350/X470 boards. I have an Asus Rog Strix B350-F. Would applying one of those old beta BIOSes improve fps for a newer Gen 4 GPU, assuming that a 5800X3D was installed?

Edit: It just occurred to me that one of those older BIOSes wouldn’t have microcode for the 5000 series. It’d be a fascinating experiment if someone could hack together a B350 bios with Gen 4 and Ryzen 5000 support…

Zedicus · February 17, 2023, 9:42pm

yes they did. i have a 5600x running on a b350 in my office, with a wx6600 GPU.

imrazor · February 17, 2023, 11:39pm

Tres cool. Do you happen to remember which motherboard and BIOS/UEFI version it was?

Zedicus · February 18, 2023, 1:57am

No and i was out the door already, i will get all the info for you on Tuesday when i am back there. I think i can check and see if the gpu reports gen 3 or 4 also.

Zedicus · February 21, 2023, 1:52pm

cool

Capture2
Capture1

imrazor · February 21, 2023, 3:43pm

Cool indeed. Have you tried a 4th gen GPU with GPU-Z?

imrazor · February 21, 2023, 3:58pm

But my own board is reporting this under Fedora 37:

00:07.1 PCI bridge: Advanced Micro Devices, Inc. [AMD] Starship/Matisse Internal PCIe GPP Bridge 0 to bus[E:B] (prog-if 00 [Normal decode])
		LnkCap:	Port #0, Speed 16GT/s, Width x16, ASPM L0s L1, Exit Latency L0s <64ns, L1 <1us
		LnkCap2: Supported Link Speeds: 2.5-16GT/s, Crosslink- Retimer+ 2Retimers+ DRS-

Information is a little sparse, but 16GT/s seems to be PCIe 4.0 bandwidth.

Zedicus · February 21, 2023, 4:40pm

The screenshot shows the gpu interface as pcie gen 4. Ihave not done more in depth Verification though.

GigaBusterEXE · February 21, 2023, 4:45pm

its unclear what the bottle neck was, I personally think it was the internal infinity fabric speeds
those first gen boards had trouble doing much past 2800mhz, limiting the 1:1 fabric speed to 1400mhz
I bet it would be fine if you ran it 2:3 ram/fabric, am5 runs the reverse 3:2
settings and speeds to try

2800Mhz RAM/2100Mhz fabric
2666Mhz RAM/2000Mhz fabric
2400Mhz RAM /1800Mhz fabric
the 2400Mhz RAM at the very least should be possible, and the Vcache should offset it

Zedicus · February 21, 2023, 7:35pm

that reminds me, i had a heck of a time finding RAM that would work on this board after the bios flash and the 5600x install. i went through 3 performance RAM kits and probably half a dozen generic sets of RAM to find something that would even boot into windows.

i thought maybe it was a bad BIOS flash or some other issue at first. but B350 with a 5xxx CPU just seems to be EXTREMELY picky on RAM settings. i will grab another pic of RAM speeds and stuff later.

Zedicus · February 21, 2023, 9:23pm

also, trying to manual set a speed, or do ANYTHING to the RAM results in a no post. it really is just a matter of finding some RAM that will post with tolerable settings and being happy with it.

B350 with 5xxx series is possible, but barely. and none of the beta BIOS seem to be getting updated.

imrazor · February 24, 2023, 7:52pm

While GPU-Z definitely reports my board as running at Gen 3 speeds, the situation is a little murkier under Linux. If you look at the output of lspci -vvv -k, it looks like the maximum link speed is 16GT/s - which should be PCIe Gen 4.

0a:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Navi 22 [Radeon RX 6700/6700 XT/6750 XT / 6800M/6850M XT] (rev df) (prog-if 00 [VGA controller])
	Subsystem: XFX Limited Device 661a
	Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr- Stepping- SERR- FastB2B- DisINTx+
	Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort- <TAbort- <MAbort- >SERR- <PERR- INTx-
	Latency: 0, Cache Line Size: 64 bytes
	Interrupt: pin A routed to IRQ 82
	IOMMU group: 18
	Region 0: Memory at e0000000 (64-bit, prefetchable) [size=256M]
	Region 2: Memory at f0000000 (64-bit, prefetchable) [size=2M]
	Region 4: I/O ports at e000 [size=256]
	Region 5: Memory at fcb00000 (32-bit, non-prefetchable) [size=1M]
	Expansion ROM at 000c0000 [disabled] [size=128K]
	Capabilities: [48] Vendor Specific Information: Len=08 <?>
	Capabilities: [50] Power Management version 3
		Flags: PMEClk- DSI- D1- D2- AuxCurrent=0mA PME(D0-,D1+,D2+,D3hot+,D3cold+)
		Status: D0 NoSoftRst+ PME-Enable- DSel=0 DScale=0 PME-
	Capabilities: [64] Express (v2) Legacy Endpoint, MSI 00
		DevCap:	MaxPayload 256 bytes, PhantFunc 0, Latency L0s <4us, L1 unlimited
			ExtTag+ AttnBtn- AttnInd- PwrInd- RBE+ FLReset-
		DevCtl:	CorrErr+ NonFatalErr+ FatalErr+ UnsupReq+
			RlxdOrd+ ExtTag+ PhantFunc- AuxPwr- NoSnoop+
			MaxPayload 256 bytes, MaxReadReq 512 bytes
		DevSta:	CorrErr+ NonFatalErr- FatalErr- UnsupReq+ AuxPwr- TransPend-
		LnkCap:	Port #0, Speed 16GT/s, Width x16, ASPM L0s L1, Exit Latency L0s <64ns, L1 <1us
			ClockPM+ Surprise- LLActRep- BwNot- ASPMOptComp+
		LnkCtl:	ASPM Disabled; RCB 64 bytes, Disabled- CommClk+
			ExtSynch- ClockPM- AutWidDis- BWInt- AutBWInt-
		LnkSta:	Speed 16GT/s, Width x16
			TrErr- Train- SlotClk+ DLActive- BWMgmt- ABWMgmt-
		DevCap2: Completion Timeout: Range ABCD, TimeoutDis+ NROPrPrP- LTR+
			 10BitTagComp+ 10BitTagReq+ OBFF Not Supported, ExtFmt+ EETLPPrefix+, MaxEETLPPrefixes 1
			 EmergencyPowerReduction Not Supported, EmergencyPowerReductionInit-
			 FRS-
			 AtomicOpsCap: 32bit+ 64bit+ 128bitCAS-
		DevCtl2: Completion Timeout: 50us to 50ms, TimeoutDis- LTR+ 10BitTagReq- OBFF Disabled,
			 AtomicOpsCtl: ReqEn+
		LnkCap2: Supported Link Speeds: 2.5-16GT/s, Crosslink- Retimer+ 2Retimers+ DRS-
		LnkCtl2: Target Link Speed: 16GT/s, EnterCompliance- SpeedDis-
			 Transmit Margin: Normal Operating Range, EnterModifiedCompliance- ComplianceSOS-
			 Compliance Preset/De-emphasis: -6dB de-emphasis, 0dB preshoot
		LnkSta2: Current De-emphasis Level: -3.5dB, EqualizationComplete+ EqualizationPhase1+
			 EqualizationPhase2+ EqualizationPhase3+ LinkEqualizationRequest-
			 Retimer- 2Retimers- CrosslinkRes: unsupported
	Capabilities: [a0] MSI: Enable+ Count=1/1 Maskable- 64bit+
		Address: 00000000fee00000  Data: 0000
	Capabilities: [100 v1] Vendor Specific Information: ID=0001 Rev=1 Len=010 <?>
	Capabilities: [150 v2] Advanced Error Reporting
		UESta:	DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
		UEMsk:	DLP- SDES- TLP- FCP- CmpltTO- CmpltAbrt- UnxCmplt- RxOF- MalfTLP- ECRC- UnsupReq- ACSViol-
		UESvrt:	DLP+ SDES+ TLP- FCP+ CmpltTO- CmpltAbrt- UnxCmplt- RxOF+ MalfTLP+ ECRC- UnsupReq- ACSViol-
		CESta:	RxErr- BadTLP- BadDLLP- Rollover- Timeout- AdvNonFatalErr-
		CEMsk:	RxErr- BadTLP- BadDLLP- Rollover- Timeout- AdvNonFatalErr+
		AERCap:	First Error Pointer: 00, ECRCGenCap+ ECRCGenEn- ECRCChkCap+ ECRCChkEn-
			MultHdrRecCap- MultHdrRecEn- TLPPfxPres- HdrLogCap-
		HeaderLog: 00000000 00000000 00000000 00000000
	Capabilities: [200 v1] Physical Resizable BAR
		BAR 0: current size: 256MB, supported: 256MB 512MB 1GB 2GB 4GB 8GB 16GB
		BAR 2: current size: 2MB, supported: 2MB 4MB 8MB 16MB 32MB 64MB 128MB 256MB
	Capabilities: [240 v1] Power Budgeting <?>
	Capabilities: [270 v1] Secondary PCI Express
		LnkCtl3: LnkEquIntrruptEn- PerformEqu-
		LaneErrStat: 0
	Capabilities: [2a0 v1] Access Control Services
		ACSCap:	SrcValid- TransBlk- ReqRedir- CmpltRedir- UpstreamFwd- EgressCtrl- DirectTrans-
		ACSCtl:	SrcValid- TransBlk- ReqRedir- CmpltRedir- UpstreamFwd- EgressCtrl- DirectTrans-
	Capabilities: [2d0 v1] Process Address Space ID (PASID)
		PASIDCap: Exec+ Priv+, Max PASID Width: 10
		PASIDCtl: Enable- Exec- Priv-
	Capabilities: [320 v1] Latency Tolerance Reporting
		Max snoop latency: 1048576ns
		Max no snoop latency: 1048576ns
	Capabilities: [410 v1] Physical Layer 16.0 GT/s <?>
	Capabilities: [440 v1] Lane Margining at the Receiver <?>
	Kernel driver in use: amdgpu
	Kernel modules: amdgpu

Could the lower speed under Windows be a driver enforced limitation?

system · November 25, 2023, 1:52pm

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