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The network cards on both PC's are set to 100Mbps Half duplex. If I set the slow PC to 100Mb Full duplex, it seems to be come just as responsive as the other PC which is set to Half duplex...

Why would half duplex on 1 PC be responsive, and slow on the other PC?


I have 2 identical computers, brand new, and have just finished setting them up using the same instruction sheet.

For some reason, the first computer is very responsive, and the second computer is very sluggish and I can't figure out why.

If I look at the windows task manager, the networking tab, I have noticed that the responsive computer makes more used of the bandwidth, i.e. I have some mapped network drives on both PCs, accessing those network drives on the responsive PC shows the graph going up and down a large amount, i.e. upto 25% for very short periods of times. However the less responsive PC, when I do the same test, the graph only goes upto 1% and it stays at 1% for long periods of times, until the task is complete.

I have looked at the network settings, and everything seems to match on both PCs, network card, driver version, settings etc etc.

So what's going now, how do I figure out why 2 computers which should be identically, setup using the same instructions, same hardware, same drivers, same os (XP), yet 1 is very slow and 1 is very responsive. Responsive as in opening windows explorer, opening applications which need a network connection.

I have even gone as far as trying the same network point for both PCs one at a time, but still, 1 is a lot more responsive than the other.

Can someone please help?

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up vote 1 down vote accepted

(This is assuming exact same hardware, software and driver versions)

If I was you, in your exact position, I would attempt to swap over the hard drives.

If the machines are identical specifications, you should be able to switch without problems.

If however the problem switches over, you are guaranteed that it is simply a setting/configuration error, so, reloading will work.

If the problem remains on the same machine, I would assume that there is some hardware issue somewhere (again, assuming all BIOS/EFI settings are the same). As the hard drive was common in both, it could identify a problem with that, but, I would bet on the network card (or motherboard if integrated).

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Before swapping out the hard drives, I timed the 2 pcs using a specific application which needs a network connection to run. PC1 = 10 seconds, PC2 = 55 seconds. Swapped out the hard drives and PC1 was still 10 seconds, and PC2 was still 55 seconds. So far I have setup up 6 identical computers and only 2 of them are responsive, the other 4 are very very slow. The network card is integrated into the motherboard. The computers are DELL optiplex 790's. – oshirowanen Sep 1 '11 at 8:04
@Oshirowanen - Thanks for trying. IMHO, next I would try to rebuild. The fact that swapping the hard drive did nothing tells me that it is either the router (which I don't believe it is) or most likely, something funky/faulty with the machine. You may also want to check the BIOS/EFI and see if there any networking settings. – William Hilsum Sep 1 '11 at 10:23
I've had a look at the BIOS settings and they match on both machines. Not sure what EFI is? – oshirowanen Sep 1 '11 at 12:05
Sorry, some modern machines have an EFI instead of BIOS, I meant check either! If the settings match, I would personally try to reinstall everything just on the off chance something went wrong, but, either these computer have some sort of failure, or, the other computers are exceptionally fast! – William Hilsum Sep 1 '11 at 12:13
why is this marked as accepted answer if it doesn't explain the problem? – eis Mar 11 '14 at 6:40

It seems that you've tracked the problem down to networking so I see two possible issues:

  1. The network interfaces on the machines aren't identical - though you appear to have ruled this out.
  2. The network ports they are plugged into are different - i.e. one is a Gigabit port the other is a 100 Megabit port (say).

Swap the network cables over (assuming they are in the same location) and see if the problem switches machine.

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Yes, for point 1, the network cards are the same make and model on both PCs. For point 2, I have tried the same network point/cable from the responsive PC, and plugged it directly into the slow PC, but the slow PC remains slow. – oshirowanen Aug 31 '11 at 12:37
Please see update 1 in original question. – oshirowanen Aug 31 '11 at 12:40

First I'd try to narrow down whether it's a hardware or software problem. So what you could do, is exchange some hardware components. If you exchange hardware X, and the responsiveness swaps, then it had something to do with X. Start with the network card (if you have a separate one) as it is the easiest (if you don't, and you are using the mainboard, do that later, as it takes longer). Try the HDD. If it has to do with the HDD, you have to figure out if it is the drive itself or your installation, so you have to exchange the OS-partitions, and so on.

Another thought: Is the slow PC also slow if the responsive is off? Does it depend on which computer you boot first?

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Please see update 1 in original question. – oshirowanen Aug 31 '11 at 12:41

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