Lower hashrate on second PC with exact same GPU [Solved]

[Mattthev]

Hi,
I'm having different hashrates on with same GPU on different PC. I have RX 470 with moded bios and stock hashrate was 580H/s. I'm mining Monero. On other PC that I bought to build mining rig it's only 480H/s. No matter if I use XMR STAK or Claymore it's almost same.
Both mobo has PCIE x16 2.0 (or should have) but the one with lower hasrates is running only on 1.1 x16 and I can't switch it in BIOS since it's OEM one. Also there are different chipsets and CPU. Both has same AMD drivers 17.4.4.
Any idea why is that? Thank you.

[1714114078]

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[1714114078]

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[1714114078]

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[1714114078]

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[Ambros]

If the software is exactly the same, the problem is obviously in hardware.
A couple ideas:
- Now enough PCIE lines on the motherboard (switch them to gen1 could help)
- Weak PSU that results in reducing power limit of GPU's

[Mattthev]

If the software is exactly the same, the problem is obviously in hardware.
A couple ideas:
- Now enough PCIE lines on the motherboard (switch them to gen1 could help)
- Weak PSU that results in reducing power limit of GPU's

Sorry I should point out I have Corsair RM850i only this 1 GPU right now. Not even 200W usage, Corsair link says 150W. It's running in 1.1 x16.
I can't switch PCIE to anything in BIOS it's pure OEM HP, didn't find any unlock or something.

So I guess I need new mobo?

Thanks for help.

[WarrEagle]

What CPU flavors are in each machine?

[Janisnader]

Which operating system do you use?

[Mattthev]

What CPU flavors are in each machine?

The fast one is i7-870 and the slow one is Core 2 Duo e7300 but I overclocked FSB to 320Mhz so now it's 3.2GHz. Also it's using only DDR2 800Mhz but now they are overclocked too I can't lower clock in BIOS... hate that OEM crap.
The slow PC is OEM HP DX 2400... but I don't think it's CPU problem usage is very low usually lower than 20% and clock speed is only about 2.4GHz (Intel Speedstep).

Slow---------------------	Fast
Core 2 Duo OC 3.2GHz	i7-870 3.5GHz auto OC to 3.6GHz I think
Asus IPIBL-LB (OEM HP)	Asus p4p55d-e
DDR2 4GB	DDR3 8GB
850W	500W
Windows 10, 17.4.4	Windows 10, 17.4.4
PCIE x16 1.1	PCIE x16 2.0

GPU is RX 470 Asus Strix 4GB with modded bios, all drivers patched. Same pool, same wallet.

Edit: the slow one is using Windows 10 Creators update...

[Mattthev]

Solved!
I've update drivers to 17.5.1 and now it's mining almost same only about 30h/s lower, so I guess there is some HW problem still, but it was main SW problem... bad drivers install maybe?
It seems like power problem of the PCIE... MSI Afterburner showing few watts lower power.

I think I will still buy new HW.
Any suggestions?
I was looking on this Gigabyte H270
I've read that MSI B250 only support 4 gpu. Is H270 support 6 PCIE devices?

Thank you guys for support. I really appreciate it.

Edit: 1 restart and I'm back in low hasrates... it makes no sense!
Edit2: another restart and mining fast again, it's like lottery!

[Mattthev]

I figure it out it's FBS problem!
After crash from OC or whatever OC setting is gone. FSB is 266MHz. Max supported is 333MHz. If I overclock to 320MHz (If I could lower RAM clocks it could goes at least to 333MHz) and reboot PC, CPU-Z detect changed FSB but other utilities didn't without reboot... I run XMR STAK with OC and gets 700h/s. On my primary PC I can get better OC (Memory goes to 2039MHz, on the lower only 2009MHz) and I have 730h/s it's about 4% difference and same for the FSB! 320MHz is 4% lower than 333MHz.
So I could upgrade CPU tu 333Mhz and even overclock that and maybe get better results, but I think I will buy new mobo. 6+ gpus is supported on Asus Z270 Prime it seems pretty good for the price for me.

Again thx guys for help. I didn't expect it would be FSB issue.