Question PC unbearably slow when new RX570 installed

[rhysiam]

So I'm a long time contributor on these forums, but I've run into an issue I just can't figure out. I'm hoping somewhere here can help.

Long post I know - but I've been working at this for many hours now so there's lots of information to impart. I'm using Spoilers to avoid a wall-of-text and hopefully help you sort the information. I'm very grateful to anyone who has the time and energy to share some ideas.

The short story is that with my new RX 570 in the system, any time Windows 10 tries to load, or a fresh Win10 installer starts, the system runs utterly, unbearably slow. More detail under the Spoilers...

Spoiler: Context

I've got an old i7 870 on a Gigbyte P55 motherboard. I've just purchased a new RX 570 to keep the old rig chugging along until I put together a new Ryzen 2 system next year. My old faithful R9 280X has been gradually dying and I can't live with the texture glitches any longer.

Spoiler: Problem

As soon the new RX 570 is connected, attempting to boot into, or install a new version of Windows 10 is utterly, unbearably slow. Like 20 minutes to load Windows. 5 seconds for a right-click to display the menu, etc. To be clear, I'm pretty sure this is not an AMD driver issue, as the unbearable performance is evident after using DDU, and when I disconnect all drives and attempt to install a fresh copy of Win10 on a blank SSD. Once I swap out the RX570 for my old 280X (which still sort of works, just glitches when I'm gaming), my existing Win10 version boots quickly, and installing Win10 onto the blank SSD is just as fast as I'd expect it to be.
Once the RX570 is back in the system, the fresh Win10 install is unbearable - It takes 45 minutes to get from the boot menu to the first dialogue option in the Windows installer. Over 5 hours yesterday I did eventually get Win10 installed, but the performance issues persist, even after the AMD driver install (which took ~90 minutes FYI).

Spoiler: Troubleshooting

I've tried the following:

• Upgraded the BIOS to the latest stable and when that didn't work, a newer beta BIOS (both are years old now, of course).
• Tried to boot with both "Optimised defaults" and "Fail Safe defaults" loaded
• I've reset the CMOS (removed the battery for 5 minutes)
• I'm confident the new RX 570 itself is fine: I tested it both in an Intel i3 6100 I borrowed, and my HTPC (a Dell H57 with an i7 860). The Dell is the same generation as my PC, so it doesn't seem like there's any endemic issue with older (pre UEFI) BIOSes. In both systems with the RX570, Win10 installed without issue and the card ran benchmarks, etc, no problems.
• Interestingly: I ran up Ubuntu 12.04 from an old disk I had lying around, and that seemed to work fine. Everything was responsive and completely usable - unlike with Windows 10.

The issue only occurs - but 100% consistently occurs - as soon as Windows 10 starts to load OR the Win10 installer starts to run whenever the RX570 is installed in my gaming system.

Spoiler: CPU is pegged at 100%

When I finally load into Windows with the RX570 installed, the CPU is pegged at 100% almost constantly. This is with an existing, or fresh install - behaviour is the same. The strange thing is, everything looks normal. Temps are fine. Clock speeds are normal, boosting into the low 3Ghz on all cores. CPU-Z (takes 15 minutes to install!) reports everything as I'd expect it to be. Everything looks fine, but it's just running dog slow. Opening File Explorer takes 20 seconds and pegs the CPU at 60-70% the whole time. Normal background processes that usually use 0-1% CPU, are hitting 10-15% and cumulatively pegging the CPU at 50-70% at idle.

Spoiler: My Suspicions

I'm currently thinking it's got to be a BIOS or compatibility issue with the card, the system and Win 10. It's a legacy (non-UEFI) BIOS. I'd welcome alternative theories or avenues to explore!

I'm happy to answer any other questions people might have. Long, long post - I'm very grateful to anyone who takes the time to read and provide suggestions!!

Spoiler: Full System Specs

• Mobo: Gigabye P55-USB3
• CPU: Intel i7 870 (all at stock throughout troubleshooting)
• Cooler: Noctua NH-D14
• Graphics: Gigabyte RX 570 (not sure exactly which model, but it's a dual fan version)
• Old Graphics: Sapphire R9 280X Dual-X
• RAM: 4x8GB GSkill 1600 (currently running stock @ 1333 for troubleshooting)
• PSU: Corsair TX 750
• Storage: I've swapping out multiple 250GB Samsung 850 EVOs with existing and fresh Win 10 installs

 

[HippoZoned]

So I can't be certain but it seems to me your card is bottlenecking your CPU or perhaps they just aren't compatible. Perhaps it's the motherboard but I don't know for sure.

However A friend had an issue like this and I told him to check his power cables because not all his power cables were fully plugged into the CPU and the power brick if modular so I'd check on that.

 

[rhysiam]

So I can't be certain but it seems to me your card is bottlenecking your CPU or perhaps they just aren't compatible. Perhaps it's the motherboard but I don't know for sure.

However A friend had an issue like this and I told him to check his power cables because not all his power cables were fully plugged into the CPU and the power brick if modular so I'd check on that.

Thanks for the post. It's not a bottleneck though. That's where a CPU is too slow to allow a GPU to run to its full potential. In this case the CPU is running abysmally with the RX 570.
I have moved multiple cards around many times through 3 systems now... the PCIe power is connected correctly -> but I did discover it won't boot when they're not!

Thanks again.

 

[rhysiam]

OK - so I've resolved the issue. I'll leave this post here in case anyone else runs into this in the future...

Turns out it's something to do with running 32GB RAM (4x8). When I drop back down to 2x8GB, all the performance problems go away immediately. I can even run my existing Windows, so no need for a reinstall. I checked though, and the Windows installer starts promptly with just 2x8GB, while I wait >20minutes to get a splash screen with 4x8GB.

I had a play around with XMP profiles and manual timings. It seems 100% consistent. Here are the scenarios:

• With my old R9 280X, I can run 4x8GB of RAM just fine. Stock, XMP and manual timings all work without issue.
• With the RX570, 4x8GB of system RAM causes the CPU to run unbearably slow despite reporting a healthy 3.2Ghz clock. This persists with stock or XMP profiles.
• With the RX570, dropping to 2x8GB of system RAM resolves the issue and works at stock, XMP, or with manual timings.

I have no explanation for why 4x8GB of system of RAM could possibly tank CPU performance. Nor why this performance issue only arises with a new graphics card. Nor why everything seemed fine when booting in Ubuntu. If someone can shed some light on this I'd be fascinated to find out!

For now though, this issue is resolved. I'm happy running 16GB RAM.

 

[Ozacle]

I have just had exactly the same as you have described, also 32gb ram. Your fix of removing the 16 has worked for me as well. I have been struggling with this for days! Now that the computer is running quicker I can try a few more things to see if I can find the actual cause and get all 32gb back again.

Thanks so much for posting your fix.

OK - so I've resolved the issue. I'll leave this post here in case anyone else runs into this in the future...

Turns out it's something to do with running 32GB RAM (4x8). When I drop back down to 2x8GB, all the performance problems go away immediately. I can even run my existing Windows, so no need for a reinstall. I checked though, and the Windows installer starts promptly with just 2x8GB, while I wait >20minutes to get a splash screen with 4x8GB.

I had a play around with XMP profiles and manual timings. It seems 100% consistent. Here are the scenarios:

• With my old R9 280X, I can run 4x8GB of RAM just fine. Stock, XMP and manual timings all work without issue.
• With the RX570, 4x8GB of system RAM causes the CPU to run unbearably slow despite reporting a healthy 3.2Ghz clock. This persists with stock or XMP profiles.
• With the RX570, dropping to 2x8GB of system RAM resolves the issue and works at stock, XMP, or with manual timings.

I have no explanation for why 4x8GB of system of RAM could possibly tank CPU performance. Nor why this performance issue only arises with a new graphics card. Nor why everything seemed fine when booting in Ubuntu. If someone can shed some light on this I'd be fascinated to find out!

For now though, this issue is resolved. I'm happy running 16GB RAM.