How accurate are broadband speed testers

[#1]

Morning all,
With speeds all over the place at the moment, I have been playing with the speedtester from the plusnet connections settings page at various times of the day.
I get the feeling that its not always accurate. Bearing in mind that my router was synced at 3008kbps yesterday and my IP profile was still set at 1750, this result seems a little wrong...

20.64Mbps eh? I think not 
A BT Speedtester result showed 1.6Mbps which is a bit more like I would expect.

[#2]

Seems pretty accurate to me....

Ok, I can dream can't I? 

[#3]

julesandtash,
Are you using Kaspersky Anti-Virus? It is known to interfere with certain Speedtest results...

[#4]

I am indeed, well Kaspersky Internet Security 2010 to be exact but close enough.
I didn't know that it interfered with results. They seem to have been OK until recently but now playing up.e
Is there any patch or workaround that you are aware of (short of turning off protection whilst I run the check)?
Cheers
Jules

[#5]

SparckZero you were certainly right. I paused protection and ran the speedtester - gave me around 1.6Mbps as does BT Speedtester.
I the ran it with Kaspersky turned on - it hovered around 600 then peaked to 2300 for a fraction of a second.
All very strange.

[#6]

Jules,
Glad to see this helped - Sadly, I'm not aware of any "proper" workaround (or why it interferes for that matter).