Intel 945 PCIe frequency setting?

[gdement]

I'm setting up an inexpensive gaming machine that will be given to my nephew at Christmas. The motherboard (MSI Neo5-F MS-7236 v2.5) and cpu (Celeron 430 1.8GHz) were an inexpensive bundle from Fry's. The video card is a Geforce 9800GT (lion's share of the budget).

The CPU runs ridiculously cold. I get the feeling I could overclock it significantly, but I'm worried about the frequency of the PCI express slot.

Googling around I've seen several comments claiming that the Intel 945 doesn't support a locked PCIe frequency. Somebody also said that even if you overclock to a standard speed (such as from 200fsb -> 266fsb) it still will end up overclocking the PCIe slot. Supposedly you have to pinmod the CPU to change the PCIe ratio.

However, the BIOS in this motherboard has a setting to manually set the PCIe frequency. I can set it to 100MHz and independently change the FSB. The motherboard is an MSI Neo5-F.

So is the motherboard a liar? Or is this limitation of the 945 a myth? Perhaps it only applies to certain versions of the chipset?

I wish I had a way to measure the PCI express frequency, but I don't. I haven't found any software utilities that will do this either. So I'm in the dark about where it's actually running.

I don't want to fry the video card by overclocking that slot. I just want to raise the FSB but leave the PCIe at the standard 100MHz. The motherboard BIOS says I can do this, but tons of random forum chatter says I can't.

Does anybody *know* how this works? Why would the bios have a manual PCIe setting if it doesn't actually work?

[Scenic]

Re: Intel 945 PCIe frequency setting?

ClockGen can read out the PCIe frequency within windows, *if you know what PLL chip is on the board*.

the original site on cpuid.com went down... "clockgen will be back soon" ... thats what they say for half a year now...
so i uploaded the version i had on my HDD



Link (328KB)
http://bambooz.pytalhost.net/badcaps...en_1.0.5.3.zip


if you know what PLL chip is on that board i would try to set the PCIe thingy in the bios to "fixed" (=100MHz default) and *slightly overclock the CPU (raising the FSB from 200MHz to 205MHz).

then boot into win and look at clockgen if the PCIe frequency is still at 100MHz.. if yes, you can OC that CPU to hell
(mine has no problems at all running overclocked from 1,8GHz to 2,8GHz without needing to set the VCore higher... i can go up to 3,4GHz with a few volts more (0,2V))

i love Core2-based CPUs

[gdement]

Re: Intel 945 PCIe frequency setting?

Thanks for the help, and for uploading that file.

I found the clock generator on the board, it's an ICS 954519BGLF.
So I set up ClockGen with the "ICS 954519" option.
It sort of works, but the numbers don't all make sense so I'm afraid I can't really draw any conclusions from it. The FSB and DDR clocks seem to read fine but the PCI and Express readings are odd.

I tried ClockGen with my FSB set at several values. The PCI Express clock is set to a fixed 100MHz in the BIOS.

The "fsb", "pcie", and "pci" values below are what ClockGen gave me. The "post card" value is the PCI frequency that was detected on my POST code reader. From past experience I know it always reads half of the actual frequency, rounded down. "F-16" is normal for a 33mhz PCI.

200:
fsb=199.01
pci=38.4
pcie=69.44
post card=f-16 (this really means it's between 32-34MHz)
(The values from ClockGen are suspect here - this is the stock setting so I should be getting normal numbers)

201:
fsb=200.5
pci=38.4
pcie=110
post card=f-18 (? quite a jump, not sure what the board is doing)

202:
fsb=201.5
pci=32.0
pcie=75.74
card=f-18

203:
fsb=202.52
pci=38.4
pcie=109.99
card=f-18

204:
fsb=203.5
pci=109.99 <impossible!>
pcie=109.99
card=f-18

205:
fsb=204.5
pci=38.4
pcie=109.99
card=f-18

206:
fsb=205.5
pci=36.0
pcie=77.24
card=f-18

207:
fsb=206.5-207.0
pci=38.4
pcie=77.62
card=f-18

208:
fsb=207.5
pci=38.4
pcie=78
card=f-18


I can't really trust the PCIe readings since the PCI values are wacky. The reading at 204FSB proves it.

However, I do see a pattern on the PCIe. If you throw out some of them, and just look at the 202, 206, 207, 208fsb, then they're increasing at a rate of 0.38MHz for every 1MHz added to the FSB. I guess that's a clue that the PCIe isn't staying fixed like the BIOS claims. Not entirely convincing since the numbers don't all make sense, but it's something.
It says Express is still well below 100MHz but I don't trust it.

[Scenic]

Re: Intel 945 PCIe frequency setting?

hmm..
there's a 519BGLF and a 519AGLF.. so i guess the tool tries to access an AGLF but its a BGLF, thus those weird values...

SetFSB has the 519BGLF in there.. so that should work better..

http://bambooz.pytalhost.net/badcaps...b_2_1_74_0.zip

[gdement]

Re: Intel 945 PCIe frequency setting?

Thanks again Scenic. I've come to the conclusion that this board just isn't going to overclock properly.

I tried SetFSB (2.1.82.0 actually) and it had the opposite issue of clockgen. It showed what seem to be correct PCI/PCIe speeds but bogus FSB/ram speeds. Anyway that's good enough.
I believe the PCI/PCIe speeds were accurate because the PCI reading was always consistent with my POST card, and I read somewhere that PCIe normally runs at 3x PCI (don't know if that's true or not). I also found some comments saying that the PCIe lock on the 945 chipset actually does exist, it just doesn't work when you move outside the officially supported bus speeds (266FSB max).

Anyway, SetFSB seemed to show that the PCIe lock was working (at 110MHz anyway), so I cranked up the speed. I didn't get very far. Either I have the worst Core2 Celeron of anybody on the internet, or it's the board.


The BIOS on this board is annoying. MSI seems to have a "daddy knows best" attitude about overclocking. They won't let you make the decisions.

Regarding the PCIe clock, if I run at stock 200MHz bus, then the PCI/PCIe are exactly what they should be: 33.3MHz/100MHz.
If I deviate by even 1MHz, then immediately the bus speed shifts to 36.7Mhz/110MHz. And then it stays locked there at any speed I set. So the lock works but MSI has chosen to stealth overclock it first, even though I entered "100MHz" as the target speed.

A much bigger problem is the RAM voltage. I'm running DDR2-800 1.8v memory, at speeds safely below spec. Yet if I increase the bus beyond 228mhz, MSI automatically forces the Vmem to 2.10v. I know some of the XTreem 0V3rClockerZ like to run that voltage, but it's insane and unnecessary here. I wanted to keep the voltage at 1.90v max, but MSI gives me no choice. Changing the RAM/FSB ratio and using SPD timings makes no difference. It's 2.1v Vmem or no overclocking for you.


That left my last option - the MSI "CoreCenter" utility. If I boot Windows at stock speed, and use the CoreCenter to raise the FSB, then I can go to any speed without changing Vmem, and PCIe even stays at the proper 100MHz. Finally.

Unfortunately, it locked when I ran Prime95 at about 245FSB. Next time I booted the machine it locked while changing speeds up to about 240FSB. I wouldn't be surprised if all these run-time speed changes are causing instability, but setting speeds in the BIOS is useless. Changing speeds in Clockgen or SetFSB doesn't work either, they just lock.
Vcore adjustments are grayed out for whatever reason.

So basically I might be able to run it at 2GHz (vs 1.8GHz stock) but I don't think I'll bother. Everything I've read online suggests these chips are normally much faster than that, so most likely it's the board/BIOS.

It's perfectly stable at stock speed though, and also when I tested it slightly over. So it'll work.

[odyssey3001]

Re: Intel 945 PCIe frequency setting?

I'm having the exact same problem with my neo5-f that I bought about a month ago. I recently tried to overclock the E7300 that I've been running on it at stock but when I pushed the FSB over 294 MHz the idiot BIOS defaulted the ram voltage to 2.1V which was plane dangerous for the 1.8V DDR2-800MHz. Contacting MSI customer service was a total waste of my time.

Were you able to use a lower memory voltage at the overclocked FSB after all?

[gdement]

Re: Intel 945 PCIe frequency setting?

I'm having the exact same problem with my neo5-f that I bought about a month ago. I recently tried to overclock the E7300 that I've been running on it at stock but when I pushed the FSB over 294 MHz the idiot BIOS defaulted the ram voltage to 2.1V which was plane dangerous for the 1.8V DDR2-800MHz. Contacting MSI customer service was a total waste of my time.

Were you able to use a lower memory voltage at the overclocked FSB after all?

No, I gave up on overclocking with the board.
I did find lots of comments on overclocker sites that imply 2.1v is maybe not a big deal, but I don't really trust gamer culture when it comes to stability.

You can keep the lower voltage if you overclock using the Windows utility, but I didn't get good results with that app.

===============
E7300 eh? My nephew bought that same processor for this motherboard a couple weeks after Christmas. It didn't work. I confirmed that it has the latest BIOS installed, the same version that MSI's web site said was required to support the chip, but it refused to POST.

So it's interesting to see that the E7300 worked for you. I have no idea what the problem was with mine, but I decided to just buy an Asus board to fix it (which advertised 45nm support right on the box). It works now but Steam decided to lock his account, so he can't play his games anyway. I feel frustrated for that kid but Steam is his problem, I want no part of that crap.

I'll sell the MSI+celeron to recoup part of the motherboard expense.